How Old Is Mr. Tortoise?

It’s Mr. Tortoise’s birthday, and he can’t wait to eat cake with his friends. But there’s a hitch! Mr. Tortoise can’t remember how old he is, so his friends don’t know how many candles to put on the cake. And they won’t stop (or slice) until they figure out the mystery.

Could Mr. Tortoise be as many years old as there are sections on his shell? He’s twice as big as the smaller tortoise . . . so is he twice as old? After the partygoers work through a variety of possibilities, they find their way to the answer with a simple bit of addition.