Permutations and Combinations
- A permutation is a particular sequence of a given set of objects. A combination is the set itself without reference to order.
- The number of different permutations of n distinct objects taken r at a time is
- The number of different combinations of n distinct objects taken r at a time is
- The number of different permutations of n objects taken n at a time, given that ni are of type i, where i = 1, 2,..., k and Σni = n, is
See also: Probability.