Combination Calculator
Result
Formula: n! / (r!(n−r)!).
Worked example: 5 choose 2 = 10; 6 choose 3 = 20.
Primary source: OpenStax Introductory Statistics, counting rules. The linked text describes the mathematical definition or method used.
How to use this tool
Enter the numbers and choose Calculate to compute combinations or permutations. Results are calculated in this browser.
Frequently asked questions
What does this calculator compute?
Free combination calculator: count exact combinations (nCr) and permutations (nPr) for whole numbers, with the formula and a worked example under the result.
Where do the inputs go?
The calculation runs in this browser; the page does not submit the entered values.
What formula is used?
The result displays the formula used: n! / (r!(n−r)!).