Significant Figures Calculator
Count & round sig figs.
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Permutation Calculator
Compute nPr — the ordered ways to choose r from n — plus combinations.
Permutations (nPr)
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Ordered selections.
| Combinations (nCr) | — |
|---|---|
| n | — |
| r | — |
| — |
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How the Permutation Calculator Works
A permutation counts the ordered ways to choose r items from n, where order matters — first, second and third place are different outcomes. The formula is nPr = n! ÷ (n−r)!. Choosing 3 from 10 in order gives 10P3 = 10×9×8 = 720 arrangements.
If order doesn’t matter, you want combinations (nCr) instead, which this calculator also shows. Permutations are always larger, by a factor of r!.
nPr = n! ÷ (n − r)!
Frequently Asked Questions
What is a permutation?
An ordered arrangement of items. The number of ways to pick r from n when order matters is nPr = n!/(n−r)!.
What is the difference between permutations and combinations?
Permutations count order (ABC ≠ CBA); combinations don’t (ABC = CBA). There are r! times as many permutations as combinations.
How many ways to arrange 3 of 10?
10P3 = 10 × 9 × 8 = 720.
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