Question

To print sum of odd numbers between 2&20

Answer 1

11+13+15+17+19

Though it can be solved,

But A short way is to use A.P.

Since it is in A.P.

Where

a=11

d=2

l=19

We know

Tn=a+(n-1)d

Hence

19=11+(n-1)2

Therefore,

n=5

Now,

Sn=n(a+l)/2

Hence,

Sn=5(11+19)/2

Hence,

Sn=75

Hope it helpz