Multiplication Priciple

The Multiplication Principle:
If an action can be performed in X1 ways, and for each of these ways another action can be performed in X2 ways, then the two actions can be performed together in X1X2 ways.
(In other words you just multiply the two or more numbers together to find out how many ways something can be done. This however is only if you do not have restrictions.)

*It helps to draw diagrams for finding how many ways especially if you have restrictions.

-Restriction:A set of rules of what you cant used or do to find your set of how many ways.

Ex1
There are 6 people sitting in chairs at a play. In how many ways can these people be arranged?
A. You should draw out six places to get an idea then draw numbers 1-6 one in each place. Notice that your restriction is that once person cannot be used twice. You do this because once a person is seated the rest can be filled by the the other people.
B.Then mulitiply all numbers in each place 1*2*3*4*5*6 =720 (this can also be expressed 6!)
C.So they're 720 ways these 6 people can be seated.