How to use the permutations and combinations calculator
Compute nPr and nCr. Enter total items n, chosen items r in the fields above; the permutations npr, combinations ncr are computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- n — Total items n
- r — Chosen items r
Worked example
With total items n = 10, chosen items r = 3, the calculator gives permutations npr ≈ 720; combinations ncr ≈ 120.
Frequently asked questions
What is the formula for the permutations and combinations calculation?
Permutations nPr = nPr(n,r). Combinations nCr = nCr(n,r). Here n is total items n, r is chosen items r.
What inputs do I need for the permutations and combinations calculator?
You need total items n, chosen items r. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.