# Function composition

Calculate the number of ways to split `n` into `k` nonempty parts.

## Syntax

```js
math.composition(n, k)
```

### Parameters

Parameter | Type | Description
--------- | ---- | -----------
`n` | Number | BigNumber |  Total number of objects
`k` | Number | BigNumber |  Number of objects in the subset

### Returns

Type | Description
---- | -----------
Number | BigNumber | The number of ways to split a set of n elements into k nonempty sets.


## Examples

```js
math.composition(8, 3);           // returns Number 21
math.composition(math.bignumber(70), math.bignumber(3)); // returns Number 2346
```


## See also

[combinations.js](combinations.md),
[stirlingS2.js](stirlingS2.md),
[bellNumbers.js](bellNumbers.md)


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