"N-Choose-K" refers to a mathematical concept used to determine the number of ways to select K items from a larger set of N items, without regard to the order of selection. The formula for calculating this is given by C(N, K) = N! / (K! * (N-K)!) where "!" denotes factorial, the product of all positive integers up to that number. This concept is widely used in various fields, including combinatorics, statistics, and probability theory. It helps in solving problems related to combinations, such as forming teams, creating groups, or selecting lottery numbers, where the arrangement of items does not matter.