what is a binomial coefficient
The binomial coefficient is the number of ways of picking unordered outcomes from possibilities, also known as a combination or combinatorial number. therefore gives the number of k-subsets possible out of a set of distinct items. For example, The 2-subsets of are the six pairs , , , , , and , so . The number of lattice paths from the origin to a point ) is the binomial coefficient (Hilton and Pedersen 1991).