# Function stirlingS2 #

The Stirling numbers of the second kind, counts the number of ways to partition a set of n labelled objects into k nonempty unlabelled subsets. stirlingS2 only takes integer arguments. The following condition must be enforced: k <= n.

If n = k or k = 1 <= n, then s(n,k) = 1 If k = 0 < n, then s(n,k) = 0

Note that if either n or k is supplied as a BigNumber, the result will be as well.

## Syntax #

```
math.stirlingS2(n, k)
```

### Parameters #

Parameter | Type | Description |
---|---|---|

`n` |
Number | BigNumber | Total number of objects in the set |

`k` |
Number | BigNumber | Number of objects in the subset |

### Returns #

Type | Description |
---|---|

Number | BigNumber | S(n,k) |

### Throws #

Type | Description —- | ———–

## Examples #

```
math.stirlingS2(5, 3) //returns 25
```