Combination

A combination is a selection of items from a set with distinct members such that the order of selection does not matter, unlike a permutation; formally, a k-combination of a set S is a subset of k distinct elements of S, and two combinations are identical exactly when they have the same members. If a set has n elements, the number of k-combinations is the binomial coefficient C(n, k), equal to n factorial divided by k factorial times (n minus k) factorial. A poker hand, for example, is a 5-combination of cards drawn from a 52-card deck, giving 2,598,960 possible hands. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/