User:Temperal/The Problem Solver's Resource5
This section cover combinatorics, and some binomial/multinomial facts.
The factorial of a number is or also as ,and is denoted by .
The number of ways of arranging distinct objects in a straight line is . This is also known as a permutation, and can be notated
The number of ways of choosing objects from a set of objects is , which is notated as either or . (The latter notation is also known as taking the binomial coefficient.
Binomials and Multinomials
Ball and Urn
The ball and urn argument states that, there are this many ways to place balls in urns: