"I like this book because it is beautiful and whimsical and colorful and fun while it teaches math, who can ask for more than that? Numbers are represented by monsters, pretty, math-y monsters."
- Capability Mom

"The concept of the book is teaching prime and composite numbers through colorful, geometrical monsters. It is written for any age, from preschool on up, and my students really appreciated it."
- Susan Midlarsky

"The most important lesson this book presents is how to reason when it comes to viewing numbers like a mathematician (and by the same token, how fun it can be to think in terms of numerical patterns)."
- MathBlog.com