Combination Calculator

Enter n (total items) and r (items chosen) to calculate the number of unordered selections.

Formula

nCr = n! ÷ (r! × (n − r)!)

Example

Choosing 2 items from a set of 5 gives 10 combinations.

Frequently Asked Questions

What's a common use case?
Combinations are used for things like lottery odds or choosing a committee, where the order of selection doesn't matter.