Question

Find the sum of all even integers between 101 and 999.

Answer 1

Given an AP is required of all integers between 101 and 999 which are even 

To find : the sum of all even integers between 101 and 999 

So, The sequence is 102, 104, 106….998 

It is an AP whose first term is 102 and d is 2 

Hence,

The sum is given by the formula s = \(\frac{n}{2}\)(2a+(n-1)d)

Now for the finding number of terms, the formula is 

Substituting n is the sum formula we get,

s = \(\frac{449}{2}\)(2 x 102 + (448) x 2)

s = 246950