Permutation & Combination

nPr and nCr with and without repetition.

Combinations (10C3)
120

order doesn't matter

Permutations (10P3)
720
With repetition (nʳ)
1,000
Combos w/ repetition
220
Show the working
  1. 1nPr = n! ÷ (n−r)! = 720
  2. 2nCr = nPr ÷ r! = 120
Formula
nPr = n!/(n−r)!, nCr = n!/(r!(n−r)!)

How it works

Counts the ways to choose or arrange r items from n — combinations ignore order, permutations count it.

Example

Choosing 3 from 10: 120 combinations, 720 permutations.

About the Permutation & Combination

nPr and nCr with and without repetition. It sits in the Math & Algebra section of NWS Calc, a free collection of calculators that run entirely in your browser. There is no signup, no paywall and no tracking — open the page, enter your numbers, get an answer.

Frequently asked questions

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What else is in Math & Algebra?
Equations, fractions, primes, roots, sequences and number theory. You can browse the full Math & Algebra category for related calculators.

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