The Cat in Numberland

The Cat in Numberland by Ivar Ekeland, 2006, 60 pages
(4th grade up)

This book is about infinity. It's funny and mind-boggling. In Hotel Infinity, each number has a room -- Room 1, Room 2, etc. In one of the stories, the odd numbers go on vacation, and the even numbers each move down to the room whose number is half theirs. The cat can't figure this out. Half the numbers are gone, but the hotel is still full! Each short story explores an aspect of infinity. The author says he got the "hotel with infinitely many rooms" idea from the mathematician David Hilbert's writings. The book is easy to read but may give you a headache if you think about it too much!