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Permutation
For other uses, see
Permutation (disambiguation).
"nPr" redirects here. For other uses, see
NPR (disambiguation).

Each of the six rows is a different permutation of three distinct balls
In
mathematics,
permutation is the act of
arranging the members of a
set into a
sequence or
order, or, if the set is already ordered,
rearranging (reordering) its elements—a process called
permuting. Permutations differ from
combinations, which are selections of some members of a set regardless of order. For example, written as
tuples, there are six permutations of the set {1,2,3}, namely: (1,2,3), (1,3,2), (2,1,3), (2,3,1), (3,1,2), and (3,2,1). These are all the possible orderings of this three-element set.
Anagrams of words whose letters are different are also permutations: the letters are already ordered in the original word, and the anagram is a reordering of the letters. The study of permutations of
finite sets is an important topic in the fields of
combinatorics and
group theory.