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A combination is an unordered selection of elements from a set. The number of ways to choose elements from a set of is the binomial coefficient .
Combinations differ from permutations in that order does not matter: and are the same combination but different permutations. The relationship is , which divides the number of -permutations by to account for the orderings of each selection.
@misc{emsenn2026-combination,
author = {emsenn},
title = {Combination},
year = {2026},
url = {https://emsenn.net/library/math/domains/number-theory/terms/combination/},
publisher = {emsenn.net},
license = {CC BY-SA 4.0}
}