Cheldelin Middle School has 12 doors to enter or leave the building. In how many ways is it possible to enter the building by one door and leave the building by a different door?

Mmmm.....not sure.....but let's see if we can maybe work to a solution ;

If we enter by any door, we have 11 possible exits

And this is true for any door...

So....we have 12 ways to enter and for each of these, 11 ways to leave

So

12 * 11 =

132 ways