1. The problem statement, all variables and given/known data 5.10. Definition. A permutation of a finite set S is a bijection from S to itself. The word form of a permutation of [n] is the list obtained by writing the image of i in position i. We write n!, read as "n factorial", to mean n*(n-1)*(n-2)* ... *2*1. 2. Relevant equations None 3. The attempt at a solution Please explain the mumbo jumbo before the last sentence.