Question

You need to arrange five of your favorite books along a small shelf. How many different ways can you arrange the books, assuming that the order of the booksmakes a difference to you?

Answer 1

For the first place in the shlef you have 5 possibilities to choose, for the second place you have 4 possibilities, for the third you have three possibilities and so on. This means that we can find the number of ways to arrange the books with a factorial, that is:

$5!=5\cdot4\cdot3\cdot2\cdot1=120$

Therefore, there are 120 ways to arrange your books in the shelf.