# Permutation of set with multiple identical items

**Consider Set S containing n elements. **

Let n_{1}, n_{2}, .....n_{r} be positive integers such that

n_{1} + n_{2} + ..... + n_{r} = n

## PROVE there exists

^{n}(R)_{n1}_{n2}..._{nr}*= { n / (n*}_{1}!n_{2}!....n_{r}!)