Permutation & Combination Calculator
Free permutation (nPr) and combination (nCr) calculator. Compute with or without repetition using exact BigInt arithmetic. Shows the formula and substitution. Instant, private, no sign-up.
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What is Permutation & Combination Calculator?
The Permutation and Combination Calculator is a free, browser-based combinatorics tool that computes permutations (nPr) and combinations (nCr) with or without repetition. It uses arbitrary-precision BigInt arithmetic so even large values stay exact, and it displays the formula and substitution used for every result. All calculations run locally in your browser — there is no sign-up and no data leaves your device.
Key Benefits
- Exact BigInt results — no floating-point overflow, even for large n and r
- All four modes in one tool: nPr and nCr, each with and without repetition
- Shows the exact formula and the numbers substituted into it
- Copy the result or download the full calculation as JSON
- 100% client-side — instant, private, and free with no sign-up
Common Use Cases
- •Probability and statistics homework in combinatorics classes
- •Calculating lottery odds — e.g. C(49, 6) for a 6/49 draw
- •Counting possible passwords, PIN codes, or arrangement of items
- •Solving permutation/combination problems for coding interviews
- •Planning menus, schedules, or selections where repetition may apply
How to Use the Permutation & Combination Calculator
- Choose the mode: Select Permutation (nPr) when order matters, or Combination (nCr) when order does not matter.
- Set repetition: Toggle repetition on if items can be chosen more than once (e.g. PIN codes, ice cream scoops), or off for distinct items.
- Enter n and r: Type the total number of items (n) and how many to choose (r). The result updates instantly with the exact formula and substitution.
- Copy or download: Copy the result to your clipboard or download the full calculation as a JSON file for reference.
Key Features
- Permutation P(n, r) — order matters
- Combination C(n, r) — order does not matter
- Toggle repetition for both modes
- Exact BigInt arithmetic, no overflow
- Shows formula with substitution
- Copy result or download as JSON