# Combinatorics#

## Scenarios#

• choose $$k$$ elements from a total of $$n$$ elements
• distribute $$k$$ elements on $$n$$ fields
Ordered Unordered
repeat $$\displaystyle n^k$$ $$\displaystyle \binom{n+k-1}{k}$$
distinct $$\displaystyle \frac{n!}{(n-k)!}$$ $$\displaystyle \binom{n}{k}$$