# Definition:Permutation/Ordered Selection/Notation

## Definition

The number of $r$-permutations from a set of cardinality $n$ is denoted variously:

${}_n P_r$
${P_n}^r$
$p_{n r}$
${}^n P_r$

There is little consistency in the literature.

On $\mathsf{Pr} \infty \mathsf{fWiki}$ the notation of choice is ${}^n P_r$.