Find the number of ways in which six teachers can be assigned to four sections of introductory mathematics if no teacher must be assigned to more than one section?

So 4 sections
6 options for first section
5 options for second (since one was used for first)
4 options
3 options
mutiply
6 times 5 times 4 times 3=360

answer is 360 ways

The first section can be taught by any one of
the 6 teachers.                               For each one . . .
The 2nd section can be taught by any one of
the remaining 5 teachers.              For each one . . .
The 3rd section can be taught by any one of
the remaining 4 teachers.              For each one . . .
The 4th section can be taught by any one of
the remaining 3 teachers.

So the number of possible teams of teachers for all four
math sections is
                
                   (6 x 5 x 4 x 3)  =  360 different teams.

Notice that whichever team is selected, there will be two teachers
who have no class to teach during the introductory math hour.