Permutation, Combination, and Binomial Theorem
Permutation
Number of possible ways to select
out of 
different elements and arrange them in a row:
Combination
Number of possible ways to select
out of 
different elements, ignoring the order and grouping together cases that differ only by the order:
Repeated permutation
Permutation where
out of
different elements are selected and repetition is allowed:
(
in some cases)Repeated combination
Combination where
out of 
different elements are selected and repetition is allowed:
(
in some cases)Circular permutation
Permutation where
different elements are arranged in a circle:
If reversal is allowed:
General circular permutation
Permutation where
out of 
different elements are selected and arranged as a circle:
Binomial theorem
Polynomial theorem
A general term of the expansion of
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