EXAMPLE 16 Computing a Permutation: Factorial Formula or Rule B?

Suppose a club has 10 members. How many slates of president, vice president, and treasurer are possible? This is a permutation. We must select three club members and arrange them in the three elective offices. In other words, we need to compute . We’ll do this in two ways. First, we’ll use the formula above and the factorial key on a calculator. Next, we’ll expand the formula, cancel, and arrive at the calculation shown for Rule B. You can decide which is easier.