Q5 of 119 Page 45

Express 81 as the sum of 9 odd numbers

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


More from this chapter

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3

Which of the following are squares of odd numbers?

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

 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)

 5

Express 100 as the sum of 10 odd numbers

 6

Write a Pythagorean triplet whose smallest member is:

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