Question

What is the sum of all the integers between 13 squared 113 squared ?

Answer 1

81515869

Explanation:

Sum of all integers between `a` and `b` (`b>=a`) `= (1+b-a)*((a+b)/2)`

`13^2=169`
`113^2=12769`

`(1+12769-169)*((12769+169)/2)=81515869`