Permutations and Combinations

Permutations: arrangements of items where the order matters EX: 2P8 = 56 2 items from 8 items = 8*7 or arrange 4 people in different ways would be 4! = 24 4*3*2*1

Combinations: arrangements of items where order does not matter EX: Person 1 and Person 2 same as Person 2 and Person 1 3C5 = 10 5*4*3 / 3*2*1
Divide out the different orders.

! = Factorial symbol EX 6! = 720 6*5*4*3*2*1

Simplify arithmetic by cancelling factors.