Find the sum of the odd numbers from 1 to 99?

the series of odd numbers from 1 to 99 :1 3 5 7 9.....99

SUM OF THE SERIES:

It is a geometric progression with a=1 and l=99 and common difference (d)=2.

let 99 be the nth term of the sequence

so, 99=1+(n-1)d

99=1+(n-1)2

solving this we get n =50.

SUM=(n/2)(a+l)

=(50/2)(1+99)

=(25)(100)

=2500.