We spotted You Can Count on Monsters at the library this week, and snatched it up because the Infant Bibliophile has been interested in both monsters and multiplication lately. If you are looking for a fun way to introduce the idea of a factor tree and prime numbers, hunt this down! (I don't recommend for the Bibliophile's age, although he has been enjoying leafing through it, but for older kids). I'm not feeling very articulate tonight, but you can click through to Amazon for the full book description and other reviews.
I'm linking this post up with Math Monday.