Sum of all integers between two integers [closed]

Answer 1

Hint:

Given two numbers A and B (both inclusive) where B > A, the sum of values between A & B is given by

B(B + 1)/2 - (A - 1)A/2
=(B^2 + B - A^2 + A)/2
=((B - A)(B + A) + (B + A))/2
=(B + A)(B - A + 1)/2

If A & B are both exclusive, then replace B with B - 1 and A with A + 1. The rest I leave it for you as an exercise

Read through the Python Expression to translate the mathematical expression to Python Code

Note Unfortunately, SO does not support MathJax or else the above expression could had been formatted better