Combinatorics Symbols
Symbol Symbol Name Meaning / definition Example
n! fractional  n! = 1·2·3·...·n 5! = 1·2·3·4·5 = 120
nPk permutation 5P3 = 5! / (5-3)! = 60
nCk

 

combination 5C3 = 5!/[3!(5-3)!]=10