Mathlean · Online math workspace

Permutations calculator

Count ordered selections without replacement using a falling factorial.

How to use this calculator

Edit both occurrences of 10 and the selection size 3 in the factorial quotient.

Tap the math below to edit it and see the result. Once a result is ready, press Tab on a hardware keyboard to accept it. Outside a matrix, Return completes the line; the phone math keyboard has the same Return action.

Try it here

10!(10−3)!\frac{10!}{(10-3)!}

Interactive tools require JavaScript. You can read the guide and example without it.

What to know

Use integers with 0 ≤ k ≤ n. Repeated indistinguishable objects need a different counting model.

Mathlean combines visual mathematical input with computation and canvas tools. Results depend on the expression and available engine support; check important answers independently.

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