Question

Brayden is organizing textbooks on his bookshelf. He has a Spanish textbook, a biology textbook, a history textbook, and a writing textbook. How many different ways can he line the textbooks up on his bookshelf?

Answer 1

Brayden has 4 textbooks.  If you think of this as positions on the shelf:

• Brayden has 4 options for the first position.
• Once he's placed the first book, he has 3 options left for the second position.
• Once he's placed the second book, he has 2 options left for the third position.
• Once he's placed the third book, he has 1 option left for the fourth position.

In total he has 4·3·2·1 ways, or 24 ways, that he can set up the books on his shelf.