Hi, there--

The Problem:
A delivery route must include stops at four cities. How many different routes are possible?

A Solution:

Each possible trip has four stops.
There are 4 ways to choose the first city on the route.
After you've chosen the first city, there are 3 ways to choose the second city.
Likewise, there are 2 ways to choose the third city.
There is only one city left to be the fourth city on your route.

Using the Fundamental Principle of Counting, we multiply
4*3*2*1 = 24

There are 24 different routes possible.

Please email me if you have questions about this solution. I'd appreciate the feedback; it will help me become a better "explainer."

Ms.Figgy
math.in.the.vortex@gmail.com