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# Permutations

A permutation of a set of distinct objects is an ordered arrangement of these objected.

For a set of $$n$$ objects, there exists $$n!$$ permutations of these.

Note: this is different to an unordered arrengement, which are Combinations.

## k-permutations

To find permutations of $$k$$ objects within a set of $$n$$, an k-permutation can be caluculated.

Given $$n, k$$ where $$0 \leq k \leq n$$. There are $P(n,k)=n(n-1)\ldots(n-k+1) = \frac{n!}{(n-k)!}$