Reverse combinations

Author
David Wales
View Count
4183
License
Creative Commons CC BY 4.0
Abstract
It's easy to find out how many combinations you can have if you know the total number of items, and the number of items you are combining. It's a little harder to do that in reverse. This document shows how to find the total number of items if you know how many are combined at a time, and the total number of combinations.
Reverse combinations