Question

the sum of first 20 odd natural numbers is equal to

Answer 1

The first odd natural no: is 1.

Now let us consider this to be in an A.P. Form.

The commom difference ,d=2. (odd numbers)

Number of terms =20.

So.
Sum = 20/2 [2(1) + (20-1)2]
=10[2+38]
=10×40=400.

So 400 is your answer....

Hope it helps...
Regards,
Leukonov.