algebra
posted by tyler .
six people are going to be seated in a row of 8 chairs. how many different ways may they be seated?

Pretend you have two extra people to fill the empty seats,
Then the number of ways to arrange them would be 8!
But the two really were not there, and the two empty seats are like having "2 like things"
so final number of arrangements = 8!/2! = 20160