Buy BOOKS at Discounted Price

Squares And Square Roots

Class 8th Mathematics RS Aggarwal Solution
Exercise 3a
  1. Using the prime factorization method, find which of the following numbers are…
  2. Show that each of the following numbers is a perfect square. In each case, find…
  3. By what least number should the given number be multiplied to get a perfect…
  4. By what least number should the given number be divided to get a perfect square…
  5. Find the largest number of 2 digits which is a perfect square.
  6. Find the largest number of 3 digits which is a perfect square.
Exercise 3b
  1. Give reason to show that none of the numbers given below is a perfect square:…
  2. Which of the following are squares of even numbers? (i) 196 (ii) 441 (iii) 900…
  3. Which of the following are squares of odd numbers? (i) 484 (ii) 961 (iii) 7396…
  4. Without adding, find the sum:(i) (1 + 3 + 5 + 7 + 9 + 11 + 13)(ii) (1 + 3 + 5 +…
  5. Express 81 as the sum of 9 odd numbers
  6. Express 100 as the sum of 10 odd numbers
  7. Write a Pythagorean triplet whose smallest member is: (i) 6 (ii) 14 (iii) 16…
  8. (i) (38)^2 - (37)^2 (ii) (75)^2 - (74)^2 (iii) (92)^2 - (91)^2 (iv) (105)^2 -…
  9. Using the formula (a + b)^2 = (a^2 + 2ab + b^2), evaluate: (i) (310)^2 (ii)…
  10. Using the formula (a - b)^2 = (a^2 - 2ab + b^2), evaluate: (i) (196)^2 (ii)…
  11. (i) 69 71 (ii) 94 106. Evaluate:
  12. (i) 88 92 (ii) 78 82. Evaluate:
  13. Fill in the blanks: (i) The square of an even number is. (ii) The square of an…
  14. Write (T) for true and (F) for false for each of the statements given below:…
Exercise 3c
  1. (23)^2 Find the value of each of the following, using the column method:…
  2. (35)^2 Find the value of each of the following, using the column method:…
  3. (52)^2 Find the value of each of the following, using the column method:…
  4. (96)^2 Find the value of each of the following, using the column method:…
  5. (67)^2 Find the value of each of the following, using the diagonal method:…
  6. (86)^2 Find the value of each of the following, using the diagonal method:…
  7. (137)^2 Find the value of each of the following, using the diagonal method:…
  8. (256)^2 Find the value of each of the following, using the diagonal method:…
Exercise 3d
  1. 225 Find the square root of each of the following numbers by using the method of…
  2. 441 Find the square root of each of the following numbers by using the method of…
  3. 729 Find the square root of each of the following numbers by using the method of…
  4. 1296 Find the square root of each of the following numbers by using the method…
  5. 2025 Find the square root of each of the following numbers by using the method…
  6. 4096 Find the square root of each of the following numbers by using the method…
  7. 7056 Find the square root of each of the following numbers by using the method…
  8. 8100 Find the square root of each of the following numbers by using the method…
  9. 9216 Find the square root of each of the following numbers by using the method…
  10. 11025 Find the square root of each of the following numbers by using the method…
  11. 15876 Find the square root of each of the following numbers by using the method…
  12. 17424 Find the square root of each of the following numbers by using the method…
  13. Find the smallest number by which 252 must be multiplied to get a perfect…
  14. Find the smallest number by which 2925 must be divided to obtain a perfect…
  15. 1225 plants are to be planted in a garden in such a way that each row contains…
  16. The students of a class arranged a picnic. Each student contributed as many…
  17. Find the least square number which is exactly divisible by each of the numbers…
  18. Find the least square number which is exactly divisible by each of the numbers…
Exercise 3e
  1. root 576 Evaluate:
  2. root 1444 Evaluate:
  3. root 4489 Evaluate:
  4. root 6241 Evaluate:
  5. root 7056 Evaluate:
  6. root 9025 Evaluate:
  7. root 11449 Evaluate:
  8. root 14161 Evaluate:
  9. root 10404 Evaluate:
  10. root 17956 Evaluate:
  11. root 19600 Evaluate:
  12. root 92416 Evaluate:
  13. Find the least number which must be subtracted from 2509 to make it a perfect…
  14. Find the least number which must be subtracted from 7581 to obtain a perfect…
  15. Find the least number which must be added to 6203 to obtain a perfect square.…
  16. Find the least number which must be added to 8400 to obtain a perfect square.…
  17. Find the least number of four digits which is a perfect square. Also find the…
  18. Find the greatest number of five digits which is a perfect square. Also find…
  19. The area of a square field is 60025 m^2 . A man cycles along its boundary at 18…
Exercise 3f
  1. root 1.69 Evaluate:
  2. root 33.64 Evaluate:
  3. root 156.25 Evaluate:
  4. root 75.69 Evaluate:
  5. root 9.8596 Evaluate:
  6. root 10.0489 Evaluate:
  7. root 1.0816 Evaluate:
  8. root 0.2916 Evaluate:
  9. Evaluate root 3 up to two places of decimal.
  10. Evaluate root 2.8 correct up to two places of decimal.
  11. Evaluate root 0.9 correct up to two places of decimal.
  12. Find the length of each side of a square whose area is equal to the area of a…
Exercise 3g
  1. root 16/81 Evaluate:
  2. root 64/225 Evaluate:
  3. root 121/256 Evaluate:
  4. root 625/729 Evaluate:
  5. root 3 13/36 Evaluate:
  6. root 4 73/324 Evaluate:
  7. root 3 33/289 Evaluate:
  8. root 80/405 Evaluate:
  9. root 1183/root 2023 Evaluate:
  10. Evaluate: root 98 x root 162
Exercise 3h
  1. Which of the following numbers is not a perfect square?A. 7056 B. 3969 C. 5478…
  2. Which of the following numbers is not a perfect square?A. 1444 B. 3136 C. 961 D.…
  3. Which of the following numbers is not a perfect square?A. 1843 B. 3721 C. 1024…
  4. Which of the following numbers is not a perfect square?A. 1156 B. 4787 C. 2704…
  5. Which of the following numbers is not a perfect square?A. 3600 B. 6400 C. 81000…
  6. Which of the following cannot be the unit digit of a perfect square number?A. 6…
  7. The square of a proper fraction is:A. Larger than the fraction B. Smaller than…
  8. If n is odd, then (1+3 +5 + 7 + ... to n terms) is equal to:A. (n^2 +1) B. (n^2…
  9. Which of the following is a Pythagorean triplet?A. (2, 3, 5) B. (5, 7, 9) C. (6,…
  10. What least number must be subtracted from 176 to make it a perfect square?A. 16…
  11. What least number must be added to 526 to make it a perfect square?A. 3 B. 2 C.…
  12. What least number must be added to 15370 to make it a perfect square?A. 4 B. 6…
  13. root 0.9 =? Choose the correct answer:A. 0.3 B. 0.03 C. 0.33 D. 0.94…
  14. root 0.1 =? Choose the correct answer:A. 0.1 B. 0.01 C. 0.316 D. None of these…
  15. root 0.9 x root 1.6 =? Choose the correct answer:A. 0.12 B. 1.2 C. 0.75 D. 12…
  16. root 288/root 128 = ? Choose the correct answer:A. root 3/2 B. 3/root 2 C. 3/2…
  17. root 2 1/4 = ? Choose the correct answer:A. 2 1/2 B. 1 1/2 C. 1 1/4 D. None of…
  18. Which of the following is the square of an even number?A. 196 B. 441 C. 625 D.…
  19. Which of the following is the square of an odd number?A. 2116 B. 3844 C. 1369…
Cce Test Paper-3
  1. root 11236 Evaluate:
  2. Find the greatest number of five digits which is a perfect square. What is the square…
  3. Find the least number of four digits which is a perfect square. What is the square root…
  4. root 0.2809 Evaluate:
  5. Evaluate root 3 correct up to two places of decimal.
  6. root 48/root 243 Evaluate:
  7. Which of the following numbers is not a perfect square?A. 529 B. 961 C. 1024 D. 1222…
  8. integrate _0^1 2/x ? Choose the correct answer:A. 2 1/2 B. 1 1/4 C. 1 1/2 D. None of…
  9. Which of the following is the square of an even number?A. 529 B. 961 C. 1764 D. 2809…
  10. What least number must be added to 521 to make it a perfect square?A. 3 B. 4 C. 5 D. 8…
  11. What least number must be subtracted from 178 to make it a perfect square?A. 6 B. 8 C.…
  12. root 72 x root 98 = ? Choose the correct answer:A. 42 B. 84 C. 9 D. 7…
  13. Fill in the blanks: (i) 1+3 +5 +7+9 +11+13 =(.)^2 (ii) root 1681 = . (iii) The…

Exercise 3a
Question 1.

Using the prime factorization method, find which of the following numbers are perfect square numbers:
(i) 441 (ii) 576

(iii) 11025 (iv) 1176

(v) 5625 (vi) 9075

(vii) 4225 (viii) 1089


Answer:

(i) 441


In order to find if the given number is a perfect square,


At first,


We’ll resolve the given number into prime factors:


Hence,


441 = 49 × 9


= 7 × 7 × 3 × 3


= (7 × 3) × (7 × 3)


= 21 × 21


= (21)2


Hence, it is a perfect square.


(ii) 576


In order to find if the given number is a perfect square,


At first,


We’ll resolve the given number into prime factors:


Hence,


576 = 64 × 9


= 8 × 8 × 3 × 3


= 2 × 2 × 2 × 2 × 2 × 2 × 3 × 3


= (2 × 2 × 2 × 3) × (2 × 2 × 2 × 3)


= 24 × 24


= (24)2


Hence, it is a perfect square.


(iii) 11025


In order to find if the given number is a perfect square,


At first,


We’ll resolve the given number into prime factors:


Hence,


11025 = 441 × 25


= 49 × 9 × 5 × 5


= 7 × 7 × 3 × 3 × 3 × 3 × 5 × 5


= (7 × 5 × 3 × 3) × (7 × 5 × 3 × 3)


= 315 × 315


= (315)2


Hence,


It is a perfect square.


(iv) 1176


In order to find if the given number is a perfect square,


At first,


We’ll resolve the given number into prime factors:


Hence,


1176 = 7 × 168


= 7 × 8 × 21


= 7 × 2 × 2 × 2 × 7 × 3


Hence,


We can see that,


The number 1176 cannot be expressed as a product of two equal numbers.


Thus,


1176 is not a perfect square.


(v) 5625


In order to find if the given number is a perfect square,


At first,


We’ll resolve the given number into prime factors:


Hence,


5625 = 225 × 25


= 9 × 25 × 25


= 5 × 5 × 5 × 5 × 3 × 3


= (5 × 5 × 3) × (5 × 5 × 3)


= 75 × 75


= (75)2


Hence,


It is a perfect square.


(vi) 9075


In order to find if the given number is a perfect square,


At first,


We’ll resolve the given number into prime factors:


Hence,


9075 = 25 × 363


= 25 × 3 × 121


= 5 × 5 × 3 × 11 × 11


= 25 × 3 × 121


Hence,


We can see that,


The number 9075 cannot be expressed as a product of two equal numbers.


Thus,


9075 is not a perfect square.


(vii) 4225


In order to find if the given number is a perfect square,


At first,


We’ll resolve the given number into prime factors:


Hence,


4225 = 25 × 169


= 5 × 5 × 13 × 13


= (5 × 13) × (5 × 13)


= 65 × 65


= (65)2


Hence,


It is a perfect square.


(viii) 1089


In order to find if the given number is a perfect square,


At first,


We’ll resolve the given number into prime factors:


Hence,


1089 = 121 × 9


= 11 × 11 × 3 × 3


= 11 × 11 × 3 × 3


= (11 × 3) × (11 × 3)


= 33 × 33


= (33)2


Hence,


It is a perfect square.


Question 2.

Show that each of the following numbers is a perfect square. In each case, find the number whose square is the given number:

(i) 1225

(ii) 2601

(iii) 5929

(iv) 7056

(v) 8281


Answer:

(i) 1225


In order to show that the given number is a perfect square,


At first,


We’ll resolve the given number into prime factors:


Hence,


1225 = 25 × 49


= 5 × 5 × 7 × 7


= (5 × 7) × (5 × 7)


= 35 × 35


= (35)2


Hence,


The given number is a perfect square.


And,


It is a perfect square of 35.


(ii) 2601


In order to show that the given number is a perfect square,


At first,


We’ll resolve the given number into prime factors:


Hence,


2601 = 9 × 289


= 3 × 3 × 17 × 17


= (3 × 17) × (3 × 17)


= 51 × 51


= (51)2


Hence,


The given number is a perfect square.


And,


It is a perfect square of 51.


(iii) 5929


In order to show that the given number is a perfect square,


At first,


We’ll resolve the given number into prime factors:


Hence,


5929 = 11 × 539


= 11 × 7 × 77


= 11 × 7 × 11 × 7


= (11 × 7) × (11 × 7)


= 77 × 77


= (77)2


Hence,


The given number is a perfect square.


And,


It is a perfect square of 77.


(iv) 7056


In order to show that the given number is a perfect square,


At first,


We’ll resolve the given number into prime factors:


Hence,


7056 = 12 × 588


= 12 × 7 × 84


= 12 × 7 × 12 × 7


= (12 × 7) × (12 × 7)


= 84 × 84


= (84)2


Hence,


The given number is a perfect square.


And,


It is a perfect square of 84.


(v) 8281


In order to show that the given number is a perfect square,


At first,


We’ll resolve the given number into prime factors:


Hence,


8281 = 49 × 169


= 7 × 7 × 13 × 13


= (13 × 7) × (13 × 7)


= 91 × 91


= (91)2


Hence,


The given number is a perfect square.


And,


It is a perfect square of 91.



Question 3.

By what least number should the given number be multiplied to get a perfect square number? In each case, find the number whose square is the new number.

(i) 3675 (ii) 2156

(iii) 3332 (iv) 2925

(v) 9075 (vi) 7623

(vii) 3380 (viii) 2475


Answer:

(i) 3675


At first,


We’ll resolve the given number into prime factors:


Hence,


3675 = 3 × 25 × 49


= 7 × 7 × 3 × 5 × 5


= (5 × 7) × (5 × 7) × 3


In the above factors only 3 is unpaired


So, in order to get a perfect square the given number should be multiplied by 3


Hence,


The number whose perfect square is the new number is as following:


= (5 × 7) × (5 × 7) × 3 × 3


= (5 × 7 × 3) × (5 × 7 × 3)


= (5 × 7 × 3)2


= (105)2


(ii) 2156


At first,


We’ll resolve the given number into prime factors:


Hence,


2156 = 4 × 11 × 49


= 7 × 7 × 2 × 2 × 11


= (2 × 7) × (2 × 7) × 11


In the above factors only 11 is unpaired


So, in order to get a perfect square the given number should be multiplied by 11


Hence,


The number whose perfect square is the new number is as following:


= (2 × 7) × (2 × 7) × 11 × 11


= (2 × 7 × 11) × (2 × 7 × 11)


= (5 × 7 × 11)2


= (154)2


(iii) 3332


At first,


We’ll resolve the given number into prime factors:


Hence,


3332 = 4 × 17 × 49


= 7 × 7 × 2 × 2 × 17


= (2 × 7) × (2 × 7) × 17


In the above factors only 17 is unpaired


So, in order to get a perfect square the given number should be multiplied by 17


Hence,


The number whose perfect square is the new number is as following:


= (2 × 7) × (2 × 7) × 17 × 17


= (2 × 7 × 17) × (2 × 7 × 17)


= (2 × 7 × 17)2


= (238)2


(iv) 2925


At first,


We’ll resolve the given number into prime factors:


Hence,


2925 = 9 × 25 × 13


= 3 × 3 × 13 × 5 × 5


= (5 × 3) × (5 × 3) × 13


In the above factors only 13 is unpaired


So, in order to get a perfect square the given number should be multiplied by 13


Hence,


The number whose perfect square is the new number is as following:


= (5 × 3) × (5 × 3) × 13 × 13


= (5 × 3 × 13) × (5 × 3 × 13)


= (5 × 3 × 13)2


= (195)2


(v) 9075


At first,


We’ll resolve the given number into prime factors:


Hence,


9075 = 3 × 25 × 121


= 11 × 11 × 3 × 5 × 5


= (5 × 11) × (5 × 11) × 3


In the above factors only 3 is unpaired


So, in order to get a perfect square the given number should be multiplied by 3


Hence,


The number whose perfect square is the new number is as following:


= (5 × 11) × (5 × 11) × 3 × 3


= (5 × 11 × 3) × (5 × 11 × 3)


= (5 × 11 × 3)2


= (165)2


(vi) 7623


At first,


We’ll resolve the given number into prime factors:


Hence,


7623 = 9 × 7 × 121


= 7 × 3 × 3 × 11 × 11


= (11 × 3) × (11 × 3) × 7


In the above factors only 7 is unpaired


So, in order to get a perfect square the given number should be multiplied by 7


Hence,


The number whose perfect square is the new number is as following:


= (3 × 11) × (3 × 11) × 7 × 7


= (11 × 7 × 3) × (11 × 7 × 3)


= (11 × 7 × 3)2


= (231)2


(vii) 3380


At first,


We’ll resolve the given number into prime factors:


Hence,


3380 = 4 × 5 × 169


= 2 × 2 × 13 × 13 × 5


= (2 × 13) × (2 × 13) × 5


In the above factors only 5 is unpaired


So, in order to get a perfect square the given number should be multiplied by 5


Hence,


The number whose perfect square is the new number is as following:


= (2 × 13) × (2 × 13) × 5 × 5


= (5 × 2 × 13) × (5 × 2 × 13)


= (5 × 2 × 13)2


= (130)2


(viii) 2475


At first,


We’ll resolve the given number into prime factors:


Hence,


2475 = 11 × 25 × 9


= 11 × 3 × 3 × 5 × 5


= (5 × 3) × (5 × 3) × 11


In the above factors only 11 is unpaired


So, in order to get a perfect square the given number should be multiplied by 11


Hence,


The number whose perfect square is the new number is as following:


=(5 × 3) × (5 × 3) × 11 × 11


= (5 × 11 × 3) × (5 × 11 × 3)


= (5 × 11 × 3)2


= (165)2



Question 4.

By what least number should the given number be divided to get a perfect square number? In each case, find the number whose square is the new number.

(i) 1575 (ii) 9075

(iii) 4851 (iv) 3380

(v) 4500 (vi) 7776

(vii) 8820 (viii) 4056


Answer:

(i) 1575


At first,


We’ll resolve the given number into prime factors:


Hence,


1575 = 7 × 25 × 9


= 7 × 3 × 3 × 5 × 5


= (5 × 3) × (5 × 3) × 7


In the above factors only 7 is unpaired


So, in order to get a perfect square the given number should be divided by 7


Hence,


The number whose perfect square is the new number is as following:


= (5 × 3) × (5 × 3)


= (5 × 3) × (5 × 3)


= (5 × 3)2


= (15)2


(ii) 9075


At first,


We’ll resolve the given number into prime factors:


Hence,


9075 = 121 × 25 × 3


= 11 × 11 × 3 × 5 × 5


= (5 × 11) × (5 × 11) × 3


In the above factors only 3 is unpaired


So, in order to get a perfect square the given number should be divided by 3


Hence,


The number whose perfect square is the new number is as following:


=(5 × 11) × (5 × 11)


= (5 × 11)2


= (55)2


(iii) 4851


At first,


We’ll resolve the given number into prime factors:


Hence,


4851 = 11 × 49 × 9


= 11 × 3 × 3 × 7 × 7


= (7 × 3) × (7 × 3) × 11


In the above factors only 11 is unpaired


So, in order to get a perfect square the given number should be divided by 11


Hence,


The number whose perfect square is the new number is as following:


=(7 × 3) × (7 × 3)


= (7 × 3)2


= (21)2


(iv) 3380


At first,


We’ll resolve the given number into prime factors:


Hence,


3380 = 4 × 5 × 169


= 2 × 13 × 13 × 2 × 5


= (2 × 13) × (2 × 13) × 5


In the above factors only 5 is unpaired


So, in order to get a perfect square the given number should be divided by 5


Hence,


The number whose perfect square is the new number is as following:


=(2 × 13) × (2 × 13)


= (2 × 13)2


= (26)2


(v) 4500


At first,


We’ll resolve the given number into prime factors:


Hence,


4500 = 4 × 125 × 9


= 2 × 2 × 3 × 3 × 5 × 5 × 5


= (5 × 3 × 2) × (5 × 3 × 2) × 5


In the above factors only 5 is unpaired


So, in order to get a perfect square the given number should be divided by 5


Hence,


The number whose perfect square is the new number is as following:


=(5 × 3 × 2) × (5 × 3 × 2)


= (5 × 2 × 3) × (5 × 2 × 3)


= (5 × 2 × 3)2


= (30)2


(vi) 7776


At first,


We’ll resolve the given number into prime factors:


Hence,


7776 = 32 × 243


= 2 × 2 × 2 × 2 × 3 × 3 × 3 × 3 × 3 × 2


= (2 × 2 × 3 × 3) × (2 × 2 × 3 × 3) × 2 × 3


In the above factors only 2 and 3 are unpaired


So, in order to get a perfect square the given number should be divided by 6


Hence,


The number whose perfect square is the new number is as following:


= (2 × 2 × 3 × 3) × (2 × 2 × 3 × 3)


= (2 × 2 × 3 × 3)2


= (36)2


(vii) 8820


At first,


We’ll resolve the given number into prime factors:


Hence,


8820 = 4 × 5 × 9 × 49


= 2 × 2 × 3 × 3 × 7 × 7 × 5


= (7 × 3 × 2) × (7 × 3 × 2) × 5


In the above factors only 5 is unpaired


So, in order to get a perfect square the given number should be divided by 5


Hence,


The number whose perfect square is the new number is as following:


=(7 × 3 × 2) × (7 × 3 × 2)


= (7 × 3 × 2)2


= (42)2


(viii) 4056


At first,


We’ll resolve the given number into prime factors:


Hence,


4056 = 8 × 3 × 169


= 2 × 2 × 13 × 13 × 3 × 2


= (13 × 2) × (13 × 2) × 6


In the above factors only 6 is unpaired


So, in order to get a perfect square, the given number should be divided by 6


Hence,


The number whose perfect square is the new number is as following:


=(13 × 2) × (13 × 2)


= (13 × 2)2


= (26)2



Question 5.

Find the largest number of 2 digits which is a perfect square.


Answer:

Let us take the first 3-digit number

First 3-digit number = 100


Now,


We know that,


100 is a perfect square.


And,


Its square root is 10.


Now,


The number before 10 is 9.


Square of 9 = 81


Hence,


The largest 2-digit number which is a perfect square is 81.



Question 6.

Find the largest number of 3 digits which is a perfect square.


Answer:

At first,

The largest 3 digit number = 999


Now,


The number whose square is 999 is 31.61 (approx.)


Hence,


The square of any number greater than 31.61 would be a 4-digit number.


Therefore,


The square of 31 will be the greatest 3 digit perfect square.


We can calculate the largest 3 digit perfect square number as:


312 = 31 × 31


= 961




Exercise 3b
Question 1.

Give reason to show that none of the numbers given below is a perfect square:

(i) 5372 (v) 360

(ii) 5963 (vi) 64000

(iii) 8457 (vii) 2500000

(iv) 9468


Answer:

(i) We know that,

A number which ends with 2 is not a perfect square


Also, the given number 5372 is ending with the digit 2


Therefore,


The given number is not a perfect square


(ii) We know that,


A number which ends with 3 is not a perfect square


Also, the given number 5963 is ending with the digit 3


Therefore,


The given number is not a perfect square


(iii) We know that,


A number which ends with 7 is not a perfect square


Also, the given number 8457 is ending with the digit 7


Therefore,


The given number is not a perfect square


(iv) We know that,


A number which ends with 8 is not a perfect square


Also, the given number 9468 is ending with the digit 8


Therefore,


The given number is not a perfect square


(v) We know that,


Any number which ends with an odd number of zeros is not a perfect square


Also, the given number 360 is ending with the digit 0


Therefore,


The given number is not a perfect square


(vi) We know that,


Any number which ends with an odd number of zeros is not a perfect square


Also, the given number 6400 is ending with the digit 0


Therefore,


The given number is not a perfect square


(vii) We know that,


Any number which ends with an odd number of zeros is not a perfect square


Also, the given number 2500000 is ending with the digit 0


Therefore,


The given number is not a perfect square



Question 2.

Which of the following are squares of even numbers?

(i) 196 (ii) 441 (iii) 900 (v) 324

(iv) 625


Answer:

(i) We know that,

The square of an even number is always even


The given number is ending with the digit 6 which is an even number


Thus, it must be a square of even number


(ii) We know that,


The square of an even number is always even


The given number is ending with the digit 1 which is an odd number


Thus, it is not square of even number


(iii) We know that,


The square of an even number is always even


The given number is ending with the digit 0 which is an even number


Thus, it must be a square of even number


(iv) We know that,


The square of an even number is always even


The given number is ending with the digit 5 which is an odd number


Thus, it is not a square of even number


(v) We know that,


The square of an even number is always even


The given number is ending with the digit 4 which is an even number


Thus, it must be a square of even number



Question 3.

Which of the following are squares of odd numbers?

(i) 484 (ii) 961 (iii) 7396 (iv) 8649 (v) 4225


Answer:

(i) We know that,

According to the property of squares, the square of an odd number is an odd number


The given number is ending with the digit 4 which is an even number


Thus, this number is not the square of an odd number.


(ii) We know that,


According to the property of squares, the square of an odd number is an odd number


The given number is ending with the digit 1 which is an odd number


Thus, this number is the square of an odd number.


(iii) We know that,


According to the property of squares, the square of an odd number is an odd number


The given number is ending with the digit 6 which is an even number


Thus, this number is not the square of an odd number.


(iv) We know that,


According to the property of squares, the square of an odd number is an odd number


The given number is ending with the digit 9 which is an odd number


Thus, this number is the square of an odd number


(v) We know that,


According to the property of squares, the square of an odd number is an odd number


The given number is ending with the digit 5 which is an odd number


Thus, this number is the square of an odd number



Question 4.

Without adding, find the sum:
(i) (1 + 3 + 5 + 7 + 9 + 11 + 13)
(ii) (1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19)
(iii) 1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19 + 21 + 23)


Answer:

(i) We know that,

Sum of first n odd numbers = n2

Applying this formula in the question, we get

(1 + 3 + 5 + 7 + 9 + 11 + 13) = (7)2

= 49

(ii) We know that,

Sum of first n odd numbers = n2

Applying this formula in the question, we get

(1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19) = (10)2

= 100

(iii) We know that,

Sum of first n odd numbers = n2

Applying this formula in the question, we get

(1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19 + 21 + 23) = (12)2

= 144


Question 5.

Express 81 as the sum of 9 odd numbers


Answer:

We know that,

Sum of first n odd numbers = n2


Expressing 81 as a sum of 9 odd numbers


81 = (9)2


n = 9


81 = 1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17



Question 6.

Express 100 as the sum of 10 odd numbers


Answer:

We know that,

Sum of first n odd numbers = n2


Expressing 100 as a sum of 10 odd numbers


100 = (10)2


n = 10


100 = 1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19



Question 7.

Write a Pythagorean triplet whose smallest member is:

(i) 6 (ii) 14 (iii) 16 (iv) 20


Answer:

(i) As we know that,

For every number m > 1, the Pythagorean triplet is (2m, m2 – 1, m2 + 1)


Using this result in the question, we get


2m = 6


m = 3


m2 = 9


m2 – 1 = 9 – 1 = 8


m2 + 1 = 9 + 1 = 10


Thus,


The Pythagorean triplet is [6, 8, 10]


(ii) As we know that,


For every number m > 1, the Pythagorean triplet is (2m, m2 – 1, m2 + 1)


Using this result in the question, we get


2m = 14


m = 7


m2 = 49


m2 – 1 = 49 – 1 = 48


m2 + 1 = 49 + 1 = 50


Thus,


The Pythagorean triplet is [14, 48, 50]


(iii) As we know that,


For every number m > 1, the Pythagorean triplet is (2m, m2 – 1, m2 + 1)


Using this result in the question, we get


2m = 16


m = 8


m2 = 64


m2 – 1 = 64 – 1 = 63


m2 + 1 = 64 + 1 = 65


Thus,


The Pythagorean triplet is [16, 63, 65]


(iv) As we know that,


For every number m > 1, the Pythagorean triplet is (2m, m2 – 1, m2 + 1)


Using this result in the question, we get


2m = 20


m = 10


m2 = 100


m2 – 1 = 100 – 1 = 99


m2 + 1 = 100 + 1 = 101


Thus,


The Pythagorean triplet is [20, 99, 101]



Question 8.

Evaluate:

(i) (38)2 - (37)2 (ii) (75)2 - (74)2

(iii) (92)2 - (91)2 (iv) (105)2 - (104)2

(v) (141)2 -(140)2 (vi) (218)2 - (217)2


Answer:

(i) We know that,

[(n + 1)2 – n2] = (n + 1) + n


(38)2 – (37)2 = 38 + 37


= 75


(ii) We know that,


[(n + 1)2 – n2] = (n + 1) + n


(75)2 – (74)2 = 75 + 74


= 149


(iii) We know that,


[(n + 1)2 – n2] = (n + 1) + n


(92)2 – (91)2 = 92 + 91


= 183


(iv) We know that,


[(n + 1)2 – n2] = (n + 1) + n


(105)2 – (104)2 = 105 + 104


= 209


(v) We know that,


[(n + 1)2 – n2] = (n + 1) + n


(141)2 – (140)2 = 141 + 140


= 281


(vi) We know that,


[(n + 1)2 – n2] = (n + 1) + n


(218)2 – (217)2 = 218 + 217


= 435


Question 9.

Using the formula (a + b)2 = (a2 + 2ab + b2), evaluate:

(i) (310)2 (ii) (508)2

(iii) (630)2


Answer:

(i) We know that,

(a + b)2 = (a2 + 2ab + b2)


We have,


3102 = (300 + 10)2


= [3002 + 2 (300 × 10) + 102]


= 90000 + 6000 + 100


= 96100


(ii) We know that,


(a + b)2 = (a2 + 2ab + b2)


We have,


5082 = (500 + 8)2


= [5002 + 2 (500 × 8) + 82]


= 250000 + 8000 + 64


= 258064


(iii) We know that,


(a + b)2 = (a2 + 2ab + b2)


We have,


6302 = (600 + 30)2


= [6002 + 2 (600 × 30) + 302]


= 360000 + 36000 + 900


= 396900



Question 10.

Using the formula (a - b)2 = (a2 - 2ab + b2), evaluate:

(i) (196)2 (ii) (689)2 (iii) (891)2


Answer:

(i) We know that,

(a – b)2 = (a2 – 2ab + b2)


We have


(196)2 = (200 - 4)2


= 2002 – 2 (200 × 4) + 42


= 40000 – 1600 + 16


= 3814


(ii) We know that,


(a – b)2 = (a2 – 2ab + b2)


We have


(689)2 = (700 - 11)2


= 7002 – 2 (700 × 11) + 112


= 490000 – 15400 + 121


= 474721


(iii) We know that,


(a – b)2 = (a2 – 2ab + b2)


We have


(891)2 = (900 - 9)2


= 9002 – 2 (900 × 9) + 92


= 810000 – 16200 + 81


= 793881



Question 11.

Evaluate:

(i) 69 × 71 (ii) 94 × 106.


Answer:

(i) We have

69 × 71 = (70 – 1) × (70 + 1)


= (702 – 12)


= 4900 – 1


= 4899


(ii) We have


94 × 106 = (100 – 6) × (100 + 6)


= (1002 – 62)


= 10000 – 36


= 9964



Question 12.

Evaluate:

(i) 88 × 92 (ii) 78 × 82.


Answer:

(i) We have

88 × 92 = (90 – 2) × (90 + 2)


= (902 – 22)


= 8100 – 4


= 8096


(ii) We have


78 × 82 = (80 – 2) × (80 + 2)


= (802 – 22)


= 6400 – 4


= 6396



Question 13.

Fill in the blanks:

(i) The square of an even number is….

(ii) The square of an odd number is…….

(iii) The square of a proper fraction is ………..than the given fraction.

(iv) n2 = the sum of first n ……. natural numbers.


Answer:

(i) The square of an even number is even

(ii) The square of an odd number is odd


(iii) The square of a proper fraction is smaller than the given fraction


(iv) n2 = the sum of first n odd natural numbers



Question 14.

Write (T) for true and (F) for false for each of the statements given below:

(i) The number of digits in a perfect square is even.

(ii) The square of a prime number is prime.

(iii) The sum of two perfect squares is a perfect square.

(iv) The difference of two perfect squares is a perfect square.

(v) The product of two perfect squares is a perfect square.


Answer:

(i) The given statement is False

As, the number of digits in a square can also be odd


e.g.: 121


(ii) The given statement is False


As, a prime number is one that is not divisible by any other number except by itself and 1


Thus, square of any number cannot be a prime number


(iii) The given statement is False


Let us take an example:


4 + 9 = 13


As, 4 and 9 are perfect squares of 2 and 3 respectively and their sum i.e., 13 is not a perfect square


(iv) The given statement is also False


Let us take an example:


36 – 25 = 11


As, 36 and 25 are perfect squares and their difference is 11 which is not a perfect square


(v) The given statement is True




Exercise 3c
Question 1.

Find the value of each of the following, using the column method:

(23)2


Answer:

Using column method, we get

Therefore,


a = 2


b = 3



Therefore,


232 = 529



Question 2.

Find the value of each of the following, using the column method:

(35)2


Answer:

Using column method, we get

Therefore,


a = 3


b = 5



Therefore,


352 = 1225



Question 3.

Find the value of each of the following, using the column method:

(52)2


Answer:

Using column method, we get

Therefore,


a = 5


b = 2



Therefore,


522 = 2704



Question 4.

Find the value of each of the following, using the column method:

(96)2


Answer:

Using column method, we get

Therefore,


a = 9


b = 6



Therefore,


962 = 9216



Question 5.

Find the value of each of the following, using the diagonal method:

(67)2


Answer:

Using diagonal method, we get:


Therefore,


672 = 4489



Question 6.

Find the value of each of the following, using the diagonal method:

(86)2


Answer:

Using diagonal method, we get


Therefore,


862 = 7396



Question 7.

Find the value of each of the following, using the diagonal method:

(137)2


Answer:

Using diagonal method, we get



Therefore,


1372 = 18769



Question 8.

Find the value of each of the following, using the diagonal method:

(256)2


Answer:

Using diagonal method, we get


Therefore,


2562 = 65536




Exercise 3d
Question 1.

Find the square root of each of the following numbers by using the method of prime factorization:

225


Answer:

By using prime factorization method, we get

225 = 3 × 3 × 5 × 5


= 3 × 5 = 15



Question 2.

Find the square root of each of the following numbers by using the method of prime factorization:

441


Answer:

By using prime factorization method, we get

441 = 3 × 3 × 7 × 7


= 3 × 7 = 21



Question 3.

Find the square root of each of the following numbers by using the method of prime factorization:

729


Answer:

By using prime factorization method, we get

729 = 3 × 3 × 3 × 3 × 3 × 3


= 3 × 3 × 3 = 27



Question 4.

Find the square root of each of the following numbers by using the method of prime factorization:

1296


Answer:

By using prime factorization method, we get

1296 = 2 × 2 × 2 × 2 × 3 × 3 × 3 × 3


= 2 × 2 × 3 × 3 = 36



Question 5.

Find the square root of each of the following numbers by using the method of prime factorization:

2025


Answer:

By resolving given number into prime factors, we get

2025 = 3 × 3 × 3 × 3 × 5 × 5


Therefore,


= 3 × 3 × 5 = 45



Question 6.

Find the square root of each of the following numbers by using the method of prime factorization:

4096


Answer:

By resolving given number into prime factors, we get

4096 = 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2


Therefore,


= 2 × 2 × 2 × 2 × 2 × 2 = 64



Question 7.

Find the square root of each of the following numbers by using the method of prime factorization:

7056


Answer:

By resolving given number into prime factors, we get

4096 = 2 × 2 × 2 × 2 × 3 × 3 × 7 × 7


Therefore,


= 2 × 2 × 3 × 7 = 84



Question 8.

Find the square root of each of the following numbers by using the method of prime factorization:

8100


Answer:

By resolving given number into prime factors, we get

4096 = 2 × 2 × 3 × 3 × 3 × 3 × 5 × 5


Therefore,


= 2 × 3 × 3 × 5 = 90



Question 9.

Find the square root of each of the following numbers by using the method of prime factorization:

9216


Answer:

By resolving given number into prime factors, we get

9216 = 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 3 × 3


Therefore,


= 2 × 2 × 2 × 2 × 2 × 3 = 96



Question 10.

Find the square root of each of the following numbers by using the method of prime factorization:

11025


Answer:

By resolving given number into prime factors, we get

4096 = 3 × 3 × 5 × 5 × 7 × 7


Therefore,


= 3 × 5 × 7 = 105



Question 11.

Find the square root of each of the following numbers by using the method of prime factorization:

15876


Answer:

By resolving given number into prime factors, we get

4096 = 2 × 2 × 3 × 3 × 3 × 3 × 7 × 7


Therefore,


= 2 × 3 × 3 × 7 = 126



Question 12.

Find the square root of each of the following numbers by using the method of prime factorization:

17424


Answer:

By resolving given number into prime factors, we get

17424 = 2 × 2 × 2 × 2 × 3 × 3 × 11 × 11


Therefore,


= 2 × 2 × 3 × 11 = 132



Question 13.

Find the smallest number by which 252 must be multiplied to get a perfect square. Also, find the square root of the perfect square so obtained.


Answer:

Resolving 252 into prime factors, we get

252 = 2 × 2 × 3 × 3 × 7


Thus, the 253 must be multiplied by 7 in order to get a perfect square


Therefore,


New number = 252 × 7 = 1764


Hence,


= 2 × 3 × 7


= 42



Question 14.

Find the smallest number by which 2925 must be divided to obtain a perfect square. Also, find the square root of the perfect square so obtained.


Answer:

Resolving 2925 into prime factors, we get

2925 = 3 × 3 × 5 × 5 × 13


Thus, 13 is the smallest number by which 2925 must be divided in order to get a perfect square


Therefore,


New number = = 225


Hence,


= 3 × 5


= 15



Question 15.

1225 plants are to be planted in a garden in such a way that each row contains as many plants as the number of rows. Find the number of rows and the number of plants in each row.


Answer:

Let the number of rows be x

Therefore,


The number of plants in each row is also x


Hence,


Total number of plants = (x × x) = x2 = 1225


x2 = 1225 = 5 × 5 × 7 × 7


x = = 5 × 7 = 35


Thus,


The total number of rows is 35 and the number of plants in each row is also 35



Question 16.

The students of a class arranged a picnic. Each student contributed as many rupees as the number of students in the class. If the total contribution is 1156, find the strength of the class.


Answer:

Let, the number of students be x

Hence,


The amount contributed by each student is Rs x


Total amount contributed = x × x = x2 = 1156


1156 = 2 × 2 × 17 × 17


x = = 2 × 17 = 34


Therefore,


The strength of class is 34



Question 17.

Find the least square number which is exactly divisible by each of the numbers 6, 9, 15 and 20.


Answer:

We know that,

The smallest number that is divisible by each o0f these numbers is their L.C.M


So,


L.C.M of 6, 9, 15, 20 = 180


Resolving into prime factors, we get


180 = 2 × 2 × 3 × 3 × 5


So, for making it a perfect square we have to multiply it by 5


Multiplying the number by 5, we get


Required number = 180 × 5


= 900



Question 18.

Find the least square number which is exactly divisible by each of the numbers 8, 12, 15 and 20.


Answer:

We know that,

The smallest number that is divisible by each o0f these numbers is their L.C.M


So,


L.C.M of 8, 12, 15, 20 = 120


Resolving into prime factors, we get


120 = 2 × 2 × 2 × 3 × 5


So, for making it a perfect square we have to multiply it by 2 × 3 × 5 = 30


Multiplying the number by 30, we get


Required number = 120 × 30


= 3600




Exercise 3e
Question 1.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method


Hence,


Using long division method,



Hence,


The square root of number is 24




Question 2.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 38



Question 3.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 67



Question 4.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 79




Question 5.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 84



Question 6.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 95



Question 7.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 107



Question 8.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 119




Question 9.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 102



Question 10.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 134



Question 11.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 140




Question 12.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 304



Question 13.

Find the least number which must be subtracted from 2509 to make it a perfect square.


Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Therefore, the number that should be subtracted from the given number to make it a perfect square is 9



Question 14.

Find the least number which must be subtracted from 7581 to obtain a perfect square. Find this perfect square and its square root.


Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Therefore, the number that should be subtracted from the given number to make it a perfect square is 12


Therefore,


Perfect square = 7581 – 12


= 7569


Therefore, its square root is 87



Question 15.

Find the least number which must be added to 6203 to obtain a perfect square. Find this perfect square and its square root.


Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Therefore, to get a perfect square than the given number we have to take the square of the next natural number of the quotient, i.e. 78


792 = 6241


Therefore,


Number that should be added to the given number to make it a perfect square = 6241 – 6203


= 38


Thus, the perfect square obtained is 6241 and its square root is 79



Question 16.

Find the least number which must be added to 8400 to obtain a perfect square. Find this perfect square and its square root.


Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



The next natural number that is a perfect square can be obtained by squaring the next natural number of the obtained quotient i.e. 91


Therefore,


(91 + 1)2 = (92)2 = 8464


Hence,


The number that should be added to the given number to make it a perfect square:


= 8464 – 8400


= 64


Thus, the perfect square obtained is 8464 and its square root is 92



Question 17.

Find the least number of four digits which is a perfect square. Also find the square root of the number so obtained.


Answer:

We have,

Smallest number of 4 digits = 1000


Using the long division method, we have



From long division method it is clear that, 1000 is not a perfect square and the obtained square root is between 31 and 32


So, by squaring the next integer we will get the perfect square


(32)2 = 1024


Thus, 1024 is the smallest four digit perfect square


As,


= 32



Question 18.

Find the greatest number of five digits which is a perfect square. Also find the square root of the number so obtained.


Answer:

We have,

Greatest five digit number = 99999


By using long division method, we get



From long division method it is clear that 99999 is not a perfect square and the square root obtained is between 316 and 317


Therefore, by squaring the smaller number we will get the perfect square that will be less than 99999


(316)2 = 99856


Hence,


99856 is the required perfect square whose square root is 316



Question 19.

The area of a square field is 60025 m2. A man cycles along its boundary at 18 km/h. In how much time will he return to the starting point?


Answer:

Given that,

Area of the square field = 60025 m2


Length of each side of the square field = = 245 m


We know that,


Perimeter of the square = 4 × sides


= 4 × 245


= 980 m


= km


It is also given that, the man is cycling at a speed of 18 km/h


Therefore,


Time =


=


= hr


= sec


= 98 × 2 sec


= 196 sec


= 3 min 16 sec




Exercise 3f
Question 1.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 1.3




Question 2.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 5.8




Question 3.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 12.5




Question 4.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 8.7




Question 5.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 3.14




Question 6.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 3.17




Question 7.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 1.04




Question 8.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 0.54



Question 9.

Evaluate up to two places of decimal.


Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 1.732


As,


= 1.732


= 1.73 (Correct up to two decimal places)



Question 10.

Evaluate correct up to two places of decimal.


Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 1.673


Therefore,


= 1.673


= 1.67 (Correct up to two decimal places)



Question 11.

Evaluate correct up to two places of decimal.


Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Hence,


The square root of number is 0.948


Therefore,


= 0.948


= 0.95 (Correct up to two decimal places)



Question 12.

Find the length of each side of a square whose area is equal to the area of a rectangle of length 13.6 meters and breadth 3.4 meters


Answer:

Given that,

Length of rectangle = 13.6 meters


Breadth of rectangle = 3.4 meters


We know that,


Area of rectangle = Length × Breadth


= (13.6 × 3.4)


= 46.24 sq m


Therefore,


Area of the square = 46.25 sq m


Length of each side of the square =


Now, by using long division method we get:



= 6.8


Therefore,


The length of a side of the square is 6.8 meters




Exercise 3g
Question 1.

Evaluate:



Answer:

We have,

=


We know that,


= 4


And,


= 9


Therefore,


=


=



Question 2.

Evaluate:



Answer:

We have,


Now, using long division method we get:



Also,



Therefore,



=


=



Question 3.

Evaluate:



Answer:

We have,


Now, by using long division method we get:



Also,



Therefore,


=


=



Question 4.

Evaluate:



Answer:

We have,

=


Now, by using long division method we get:


= 25



Also,


= 27



Therefore,


=


=



Question 5.

Evaluate:



Answer:

We have,

=


=


=


=


= 1



Question 6.

Evaluate:



Answer:

We have,

=


=


Now, using long division method we get:


= 37



Also,


=


= 2 × 9


= 18


Therefore,


= =


= 2



Question 7.

Evaluate:



Answer:

We have,


=


=


Now, by using long division method we get:



= 17


Also,


=


= 2 × 5 × 3


= 30


Therefore,


=


= 1



Question 8.

Evaluate:



Answer:

We have,


=


=


=



Question 9.

Evaluate:



Answer:

We have,

=


=


=


=


=



Question 10.

Evaluate:



Answer:

We have,


=


=


= 2 × 7 × 9


= 126




Exercise 3h
Question 1.

Which of the following numbers is not a perfect square?
A. 7056

B. 3969

C. 5478

D. 4624

Hint. The number 5478 ends in 8.


Answer:

We know that,

As per the properties of square,


All the numbers that end with digits 2, 3, 7 or 8 are not a perfect square


Hence,


Considering the property, we get


The number 5478 is not a perfect square


As the last digit of the number is 8.


Therefore,


Option (C) is the correct option


Question 2.

Which of the following numbers is not a perfect square?
A. 1444

B. 3136

C. 961

D. 2222

Hint. The number 2222 ends in 2.


Answer:

We know that,

As per the properties of square,


All the numbers that end with digits 2, 3, 7 or 8 are not a perfect square


Hence,


Considering the property, we get


The number 2222 is not a perfect square


As the last digit of the number is 2.


Therefore,


Option (D) is the correct option.


Question 3.

Which of the following numbers is not a perfect square?
A. 1843

B. 3721

C. 1024

D. 1296

Hint. The number 1843 ends in 3.


Answer:

We know that,

As per the properties of square,


All the numbers that end with digits 2, 3, 7 or 8 are not a perfect square


Hence,


Considering the property, we get


The number 1843 is not a perfect square


As the last digit of the number is 3.


Therefore,


Option (A) is the correct option.


Question 4.

Which of the following numbers is not a perfect square?
A. 1156

B. 4787

C. 2704

D. 3969

Hint. The number 4787 ends in 7.


Answer:

We know that,

As per the properties of square,


All the numbers that end with digits 2, 3, 7 or 8 are not a perfect square


Hence,


Considering the property, we get


The number 4787 is not a perfect square


As the last digit of the number is 7.


Therefore,


Option (B) is the correct option.


Question 5.

Which of the following numbers is not a perfect square?
A. 3600

B. 6400

C. 81000

D. 2500

Hint. The number 81000 ends in an odd number of zeros.


Answer:

We know that,

As per the properties of square,


All the numbers that end with odd numbers of zeroes are not a perfect square


Hence,


Considering the property, we get


The number 81000 is not a perfect square


As the number of zeroes of this number is 3.


Therefore,


Option (C) is the correct option.


Question 6.

Which of the following cannot be the unit digit of a perfect square number?
A. 6

B. 1

C. 9

D. 8


Answer:

We know that,

As per the properties of square,


A number which is a perfect square cannot have 2, 3, 7 or 8 as their unit digit.


Hence,


Considering the property, we get


That 8 cannot be the unit digit of a perfect square number


Therefore,


Option (D) is the correct option.


Question 7.

The square of a proper fraction is:
A. Larger than the fraction

B. Smaller than the fraction

C. Equal to the fraction

D. None of these


Answer:

We know that,

Proper fraction is a fraction that is less than 1, where the numerator is less than the denominator.


Hence,


We can observe that,


The square of any proper fraction will be smaller than the original fraction.


Therefore,


Option (B) is the correct option.


Question 8.

If n is odd, then (1+3 +5 + 7 + ... to n terms) is equal to:
A. (n2 +1)

B. (n2 —1)

C. n2

D. (2n2 +1)


Answer:

We know that,

In the given series,

a = 1, d = 3 - 1 = 2

Sum of n numbers =


=


=


=


= n2


Hence,


Option (C) is the correct option.


Question 9.

Which of the following is a Pythagorean triplet?
A. (2, 3, 5)

B. (5, 7, 9)

C. (6, 9, 11)

D. (8, 15, 17)


Answer:

We know that,

According to the Pythagorean triplet,


For a natural number m,


(2m, m2 – 1, m2 + 1) is a Pythagorean triplet.


Hence,


Considering the Pythagorean triplet,


Let m = 4


2m = 8


m2 – 1 = 15


m2+ 1 = 17


Thus,


(8, 15, 17) is the Pythagorean triplet.


Hence,


Option (D) is the correct option.


Question 10.

What least number must be subtracted from 176 to make it a perfect square?
A. 16

B. 10

C. 7

D. 4


Answer:

For making 176 a perfect square we have to subtract 7 from it as:

176 – 7 = 169


And, we know that:


= 13


Therefore, option (C) is correct


Question 11.

What least number must be added to 526 to make it a perfect square?
A. 3

B. 2

C. 1

D. 6


Answer:

For making 526 a perfect square we have to add 3 on it as:

526 + 3 = 529


And, we know that:


= 23


Therefore, option (A) is correct


Question 12.

What least number must be added to 15370 to make it a perfect square?
A. 4

B. 6

C. 8

D. 9


Answer:

For making 15370 a perfect square we have to add 6 on it as:

15370 + 6 = 15376


And, we know that:


= 124


Therefore, option (B) is correct


Question 13.

Choose the correct answer:

=?
A. 0.3

B. 0.03

C. 0.33

D. 0.94


Answer:

By using long division method, we have


Hence, option (D) is correct


Question 14.

Choose the correct answer:

=?
A. 0.1

B. 0.01

C. 0.316

D. None of these


Answer:

By using long division method, we have


Therefore, option (C) is correct


Question 15.

Choose the correct answer:

=?
A. 0.12

B. 1.2

C. 0.75

D. 12

Hint. = 1.2


Answer:

We have,

× =


Also,


= 1.2


Hence, option (B) is correct


Question 16.

Choose the correct answer:


A.

B.

C.

D. 1.49

Hint.


Answer:

We have,

=


=


=


=


=


Therefore, option (C) is correct


Question 17.

Choose the correct answer:


A.

B.

C.

D. None of these

Hint.


Answer:

We can solve the given question as:

=


=


=


=


=


=


Hence,


Option (B) is the correct option


Question 18.

Which of the following is the square of an even number?
A. 196

B. 441

C. 625

D. 529


Answer:

As we know that,

Square of an even number is always an even number.


Hence,


196 is the square of an even number.


Therefore,


Option (A) is the correct option.


Question 19.

Which of the following is the square of an odd number?
A. 2116

B. 3844

C. 1369

D. 2500


Answer:

As we know that,

Square of an odd number is always an odd number.


Hence,


1369 is the square of an odd number.


Therefore,


Option (C) is the correct option.



Cce Test Paper-3
Question 1.

Evaluate:



Answer:

According to question,

In order to find the square root of the given number we will use the long division method.


Hence,


Using long division method,



Therefore,


= 106



Question 2.

Find the greatest number of five digits which is a perfect square. What is the square root of this number?


Answer:

We know that,

Greatest five digit number = 99999


Now, by using long division method we get:



From above results it is clear that:


316 < < 317


Therefore,


(316)2 = 99856


Hence, 99856 is the least four digit perfect square number having square root 316




Question 3.

Find the least number of four digits which is a perfect square. What is the square root of this number?


Answer:

We know that,

Least four digit number = 1000


Now, by using long division method we get:



From above results it is clear that:


31 < < 32


Therefore,


(32)2 = 1024


Hence, 1024 is the least four digit perfect square number having square root 32



Question 4.

Evaluate:



Answer:

By using long division method we get:


Therefore,


= 0.53



Question 5.

Evaluate correct up to two places of decimal.


Answer:

We have,


Now, by using long division method we get:



Therefore,


= 1.732


Hence,


The value of up to 2 decimal places is 1.73



Question 6.

Evaluate:



Answer:

We have,

=


=


=


=


=



Question 7.

Which of the following numbers is not a perfect square?
A. 529

B. 961

C. 1024

D. 1222


Answer:

We know that,

Any number which is ending with 2, 3, 7 and 8 is not a perfect square


Therefore,


1222 is not a perfect square as it is ending with digit 2


Hence, option (D) is correct


Question 8.

Choose the correct answer:

?
A.

B.

C.

D. None of these


Answer:

We have,

=


=


=


=


= 1


Therefore, option (C) is correct


Question 9.

Which of the following is the square of an even number?
A. 529

B. 961

C. 1764

D. 2809


Answer:

We know that,

The square of an even number is always number


Hence, 1764 is the square of an even number as it is ending with the digit 4 which is even


Therefore, option (C) is correct


Question 10.

What least number must be added to 521 to make it a perfect square?
A. 3

B. 4

C. 5

D. 8


Answer:

For making 521 a perfect square, we have to add 8 on it as:

521 + 8 = 529


And we know that,


= 23


Hence, option (D) is correct


Question 11.

What least number must be subtracted from 178 to make it a perfect square?
A. 6

B. 8

C. 9

D. 7


Answer:

For making 178 a perfect square we have to subtract 9 from it as:

178 – 9 = 169


And we know that,


= 13


Therefore, option (C) is correct


Question 12.

Choose the correct answer:


A. 42

B. 84

C. 9

D. 7


Answer:

We have,

× = ×


=


= 2 × 2 × 3 × 7


= 84


Hence, option (B) is correct


Question 13.

Fill in the blanks:

(i) 1+3 +5 +7+9 +11+13 =(…….)2

(ii) = ……….

(iii) The smallest square number exactly divisible by 2, 4, 6 is

(iv) A given number is a perfect square having n digits, where n is odd. Then, its square root will have …………… digits.


Answer:

(i) We have,

1 + 3 + 5 + 7 + 9 + 11 + 13


We know that,


Sum of first n odd numbers = n2


Therefore,


1 + 3 + 5 + 7 + 9 + 11 + 13 = (7)2


(ii) By using long division method, we have



Therefore,


= 41


(iii) We know that,


The smallest square number which is exactly divisible by 2, 4 and 6 is 36


Also,


L.C.M of 2, 4b and 6 is 12


Prime factorization of 12 = 2 × 2 × 3


Now, for making it a perfect square we have to multiply it by 3


Therefore,


12 × 3 = 36


(iv) We know that,


A given number is a perfect square having n digits, where n is odd. Then, its square root will have () digits