### Home > A2C > Chapter 10 > Lesson 10.2.3 > Problem 10-94

10-94.

Here is another way to think about the question: “*What is *?”

How many ways are there to choose all five items from a group of five items? What happens when you substitute into the factorial formula to compute

? Since you know (logically) what the result has to be, use this to explain whatmust be equal to. On the other hand, how many ways are there to choose

*nothing*from a group of five items? And what happens when you try to use the factorial formula to compute?See part (a).