# Permutations and Combinations Formula

Both the permutation and combination deals with computing the number of possible ways to arrange a set of elements. Permutation is an arrangements of different elements in an ordered sequence, whereas combination is grouping the different elements in any order, here order does not matter.

**Below are basic permutation and combination formulas:**

1. Permutation =

*n*$P_{r}$ = $\frac{n!}{(n-r)!}$.2. Permutation with repetition =

*n*$^{r}$.3. Combination = n$C_{r}$ = $\frac{nP_{r}}{n!}$.

4. When permutation is not related, combination = n$C_{r}$ = $\frac{n!}{(n-r)!r!}$.

Where, n = total size of the elements, r = number of permutation.