What is a shortcut for finding the sum of all numbers from 1-99?

Answer 1

There is quite the easy shortcut for adding any set of numbers from 1 to whatever and that is this:

(n(n+1))/2

So, let's say you wanted to find the sum of all numbers from 1 to 99. 99 will be n and so the equation will look like the following:

(99(99+1))/2

Solve for the top first:

9900/2

Finish the solution:

9900/2 = 4950

And there you go, you can use and number greater than one as your n.