Question

What is the sum of the first 500 odd numbers?

Answer 1

a1=1

a2=3

common difference= a2-a1

=3-1

=2.

n=500

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

=500/2[2×1+(500-1)2]

=250[2+(499)2]

=250[2+998]

=250[1000]

=250000