Question

formula for sum of all odd no. from 1 to 100.

Answer 1

50/2(1+99)...............
n/2(a+an)

Answer 2

All odd numbers follow an AP

1+3+5+7....99

with a=1,d=2 and n=50

Club in the formula:

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

=50/2*(1+(50-1)*2)

=25*(1+98)

=25*99

=2475

Thats the answer