CBSE NCERT Solutions for Class 8 Chapter 6

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CBSE NCERT Solutions for Class 8 Maths Chapter 6:

Question-1:

What will be the unit digit of the squares of the following numbers:
(i) 81 (ii) 272
(iii) 799 (iv) 3853
(v) 1234 (vi) 26387
(vii) 52698 (viii) 99880
(ix) 12796 (x) 55555

Solution:

(i) The number 81contains its unit’s place digit 1.So, square of 1is 1.
Hence, unit’s digit of square of 81 is 1.

(ii) The number 272 contains its unit’s place digit 2. So, square of2is 4.
Hence, unit’s digit of square of 272 is 4.

(iii) The number 799 contains its unit’s place digit9. So, square of 9 is 81.
Hence, unit’s digit of square of 799 is 1.

(iv) The number 3853contains its unit’s place digit 3. So, square of3is 9.
Hence, unit’s digit of square of 3853 is 9.

(v) The number 1234 contains its unit’s place digit 4. So, square of 4is 16.
Hence, unit’s digit of square of 1234 is 6.

(vi) The number 26387contains its unit’s place digit 7. So, square of 7is49.
Hence, unit’s digit of square of 26387 is 9.

(vii) The number 52698contains its unit’s place digit 8. So, square of8 is64. Hence,
unit’s digit of square of 52698 is 4.

(viii) The number 99880 contains its unit’s place digit 0. So, square of 0is 0. Hence,
unit’s digit of square of 99880is 0

(ix) The number 12796contains its unit’s place digit 6.
So, square of 6is36. Hence, unit’s digit of square of 12796 is 6.

(x) The number 55555contains its unit’s place digit 5. So, square of5is25. Hence, unit’s digit
of square of 55555 is 5.

Question-2:

The squares of which of the following would be odd number:
(i) 431 (ii) 2826
(iii) 7779 Iv) 82004

Solution:

(i) 431– Unit’s digit of given number is 1and square of 1is 1. Therefore, square of 431 would be an odd number.

(ii) 2826– Unit’s digit of given number is 6 and square of 6 is 36. Therefore, square of 2826 would not be an odd number.

(iii) 7779–Unit’s digit of given number is 9 and square of 9 is 81.Therefore, square of 7779 would be an odd number.

(iv) 82004– Unit’s digit of given number is 4 and square of 4 is 16.Therefore, square of 82004 would not be an odd number.

Question-3:

(i) Express 49 as the sum of 7odd numbers.
(ii) Express 121as the sum of 11oddnumbers.

Solution:

(i) 49is the square of 7. Therefore it is the sum of 7 odd numbers.
49= 1 +3+ 5 + 7 + 9 +11+ 13

(ii) 121 is the square of11. Therefore it is the sum of 11odd numbers
121 = 1+3 +5 +7 + 9+11+13+15 + 17 + 19+ 21