A variation in combinatorics is an ordered selection of k elements chosen from n elements without repetition.
Number of variations (without repetition)
$$V_{n}^{k}=\frac{n!}{(n-k)!}$$
where,
n— number of elements;
k— number of selected elements.
Number of variations (with repetition)
$$\overline{V}_{n}^{k}=n^{k}$$
where,
n— number of elements;
k— number of selected elements.
