▣ CALCULATORS Updated July 25, 2026

Permutation and Combination Calculator

nPr and nCr for any pair of values.

n (total items)
r (chosen)
Result
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How it works

Permutations count ordered selections, n! / (n − r)!, while combinations count unordered selections, n! / (r! (n − r)!). Both are computed iteratively to avoid overflow.

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Frequently asked questions

When do I use combinations?

When order does not matter, such as choosing 5 lottery numbers from 49.

When do I use permutations?

When order matters, such as ranking the top three finishers in a race.

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