Question

You need to put your reindeer, Jebediah, Lancer, Ezekiel, Gloopin, and Bloopin, in a single-file line to pull your sleigh. However, Lancer and Ezekiel are best friends, so you have to put them next to each other, or they won't fly.

How many ways can you arrange your reindeer?

Answer 1

48

Explanation:

Khan Academy

Answer 2

Well to start out you have 5 reindeer. If you glue Lancer and Ezekiel together you only have 4 units to arrange in different orders. That number is 24. But for each of those, Lancer and Ezekiel can be arranged in two ways... with Lancer in front of the pair or in the back of the pair. So altogether there are 48 ways to arrange the five reindeer with Lancer and Ezekiel always being together.