Answer:
120
Step-by-step explanation:
There are 5 different ways to put the first book
Now there are 4 books left
There are 4 different ways to put the second book
Now there are 3 books left
There are 3 different ways to put the third book
Now there are 2 books left
There are 2 different ways to put the fourth book
Now there are 1 book left
5*4*3*2*1
120