You rent 4 movies. All are different categories. How many orders can you watch them in?

Question

There are friends over and you rent 4 movies. One comedy, one animated, one action and one science fiction. How many orders can you watch the movies in? 

Answer 1

4*3*2*1=24 different ways to watch them

the movies are A, B, C, and D

watch movie A first

ABCD

ABDC

ACBD

ACDB     

ADBC

ADCB

 

now watch movie B first and come up with 6 more ways

BACD

BADC

BCAD

BCDA

BDAC

BDCA

do the same for movie C and movie D to get 6+6=12 more ways for a total of 24 ways