Jessica looked at her collection of books. There was Musical Knights, Space Knights, Fantastic Mr. Knight, The Big Smelly Knight, Space Knight II (The Sequel), One of our Knight is Missing, The Knight of Delights, Mysterious Knight, and lastly her favourite, The Day the Knight Exploded.
She started to arrange the books on the shelf, and then thought to herself... 'If I placed each book side by side, I wonder how many different combinations I could arrange these books in...'.
How many combinations are there?
To The Answer