# Function permutations Compute the number of ways of obtaining an ordered subset of `k` elements from a set of `n` elements. Permutations only takes integer arguments. The following condition must be enforced: k <= n. ## Syntax ```js math.permutations(n) math.permutations(n, k) ``` ### Parameters Parameter | Type | Description --------- | ---- | ----------- `n` | number | BigNumber | The number of objects in total `k` | number | BigNumber | The number of objects in the subset ### Returns Type | Description ---- | ----------- number | BigNumber | The number of permutations ### Throws Type | Description ---- | ----------- ## Examples ```js math.permutations(5) // 120 math.permutations(5, 3) // 60 ``` ## See also [combinations](combinations.md), [combinationsWithRep](combinationsWithRep.md), [factorial](factorial.md)