Permutations & Combinations Practice (Free)

Practice permutations and combinations with this free tool. It asks how many ways to arrange or choose items, checks your answer instantly, and shows the formula expanded.

How the practice works

1. Pick a difficulty.
2. Compute the count and press Check.
3. Read the feedback and step-by-step solution, then press Next.

Arrange vs. choose

When order matters, use permutations: nPr = n!/(n − r)!. When order doesn’t matter, use combinations: nCr = n!/(r!(n − r)!). The solution panel shows which one applies and expands it.

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Frequently asked questions

When do I use a permutation vs. a combination?

Use a permutation when order matters (arrangements) and a combination when it doesn’t (selections).

Is it free?

Yes — unlimited problems, no sign-up, with progress saved in your browser.

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Does it show the formula?

Yes — each answer expands nPr or nCr step by step.

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Read the full lesson: learn the method step by step.

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