Question

How many consecutive odd numbers from 1 are to be added to get a sum 729

Answer 1

Answer:

1+3+5+7+9+11+13+15+17+19+21+23= 23 numbers .

Square is 729.

Answer 2

Required n=27

Given,

a=1

d=2

n=?

S n=729

Therefore,

S n=n/2[2a+( n - 1)d]

729=n/2[2×1+( n - 1)2]

729=n/2(2+2n-2)

729=n/2(2n)

729=n✓

n =√729

n=27