Math Formulas
Permutation Formulas
$ P \left ( \text{n}, \text{r} \right )={^ \text{n}P_ \text{r}}= \dfrac{ \text{n}!}{\left ( \text{n}- \text{r} \right )!} $
Where,
n, r are non negative integers and r ≤ n.
r is the size of each permutation.
n is the size of the set from which elements are permuted.
! is the factorial operator.
Factorial :
$\text{n}!=\text{n}\;(\text{n}-1)\;(\text{n}-2)$ $(\text{n}-3)\;(\text{n}-4) \;... $