* For this one, order does NOT matter!
We did this problem before:
If we have 8 books, how many ways can we arrange 3 on a
We figured it out with slots:
But, using the formula gave us the same thing:
Here's a different question for you:
If we have 8 books and we want to take 3 on vacation with us, how
many ways can we do it?
What's the difference between these problems?
ORDER DOESN'T MATTER!
In the first problem, we were arranging the 3 books on a shelf... and in the second problem, we're just tossing the 3 books in a suitcase.
So, if order doesn't matter, we'll just divide it out!
Arranging the 3 books is 3!