I purchased this book at a college book store. I think it was there because it was required reading for math education majors. It also might have been a book for elementary teachers that were taking a math methods course. Regardless of why it was there, I purchased it and read it. It was a fun and interesting look at lots of different math topics.

My son has enjoyed this book since he was about 9 years old. He has probably read it cover to cover at least 5 times and recommends it to all of his friends that like math as much as he does.

You really can't beat it for the price! It's perfect for pre-teens that love math.

what a great way to learn about fibonaci, infinite series, and the aesthetics of mathematics. for young and old, a definite read for anyone interested in the universal.

I had been concerned that my ten year old son wasn't reading as much as he used to. His reading lexile has been off the chart, 1300+ I believe, since 3rd grade, so it has been hard to find books that are challenging and yet age-appropriate. He was glued to this book for the three days that it took to read it, and he actually thanked me for getting it for him. Thanks, Amazon for putting on the recommended list.

THE BOOK WAS EASY TO READ AND DID GIVE MY SON A BETTER UNDERSTANDING OF NUMBERS AND HOW THEY RELATE TO EACH OTHER. THE STORY WAS INTERESTING AND THE DESCRIPTIONS WERE GREAT. I DID FIND THAT SOMETIMES HE HAD TO REREAD SOME OF IT TO COMPREHEND WHAT WAS BEING SAID. THE MATH PART WAS NOT AS DETAILED AS IT SHOULD HAVE BEEN.

My son refused to look at this when he saw the title had Number in it, so I began reading it to my daughter instead. Soon he was listening intently and then asking to see the pictures or diagrams. The book doesn't teach how to do math, but more the logical constants of math. Numbers become predictable friends instead of tricky foes. Because it pits the boy against the devil, it appeals to boys competitive spirit. And you can go back to chapters again and again to gain a deeper understanding without getting bored. The practical applications of what they are doing with numbers are a little harder to grasp in this book, but it is a fun read.

This is a fabulous novel all about numbers: their history, their use, and their mystery! It is a must read! :)

Unfortunately, my daughter says this is a yawn. It is informative but very boring. She says it tries to be creative and make math fun, but it is "not fun."

My 9 year old read this book and then extended her borrowing time so that I could also read it. I enjoyed the format with each chapter being based on one of his dreams.

I think the book can open kids' eyes open to the relevance of numbers and mathematics. It's engaging and funny.

My 6th grade math-hating students, the students who struggle with math and have little number sense, love hearing this book while drawing reflections and using calculators to crunch the numbers. They are starting to look at numbers in a new way.

My 6th grade math-hating students, the students who struggle with math and have little number sense, love hearing this book while drawing reflections and using calculators to crunch the numbers. They are starting to look at numbers in a new way.

This is a really neat book for kids who think math makes no sense/

A wonderful well written book that is sure to capture your interest.

A wonderful well written book that is sure to capture your interest.

This is without question one of the best children's books with a mathematical theme ever written. It is witty, charming and fun for children and actually teaches them some mathematics along the way. Not just the simple math of one and one is two; very complex ideas such as infinity, Fibonacci numbers, and Pascal's triangle are described in ways that elementary school children can understand. I couldn't put it down as I read through and marveled at the ability of the author to explain these mathematical concepts.
The illustrations are very much like those in other children's books; the number devil himself looks like a smug college professor. With the glasses, bushy eyebrows, a tie, goatee beard and short pants, if you take away the horns he reminds you of an eccentric teacher. I am not scheduled to teach our course in the fundamentals of arithmetic, but if it comes time to do so again, I will use this book as a supplement in the class.

This is a great book for everyone. My son 7, who is very interested in math loved it. The only drawback is the use of words like rutabaga instead of square root, unreasonable numbers instead of irrational munbers etc. If your child can live with that, this is a great learning tool. The dreams are cute fantasies. A nice way to incorporate math into a fictional book. I would recommend it for about 4th -6th grade, or younger if your child is particularily interested in math.

This is a great book for everyone. My son 7, who is very interested in math loved it. The only drawback is the use of words like rutabaga instead of square root, unreasonable numbers instead of irrational munbers etc. If your child can live with that, this is a great learning tool. The dreams are cute fantasies. A nice way to incorporate math into a fictional book. I would recommend it for about 4th -6th grade, or younger if your child is particularily interested in math.

When I first got this I thought was going to be very boring because it's about math. But once I started reading it I couldn't get my eyes off of it! It teaches different tricks to work out math problems in a fun way. If you or your kids are struggling in some areas in math as well as trying to find an entertaining book to read this is the perfect book.

This was a terrific find. My math hesitant child is actually enjoying the story. The fact that concepts (some fairly high level)are sneaked in is quite creative. I highly recommend this book to anyone trying to interest their child in math.

I read this book knowing that is was targeted at a younger age than I. However, I was not disappointed. The book contains colorful and often helpful illustrations, and the story isn't half bad, if not a bit monotonous. It also has fun and interesting mathematical tricks and facts, as well as a little of the basics. I found the idea of a Number Hell and Heaven very funny and interesting. There were only two problems that I had with this book:
1. The mathematics presented in each chapter varies greatly. In the first few chapters, simple math, or "the basics" are reviewed. Then, after a few chapters, the book suddenly jumps to more complicated math, like factorials, basic geometry, infinity theory, and more. It looks like half the book is for 8-12 year-olds, and half of it is for 13-14 year-olds. The jump is very sudden, and depletes the book of it's easy-to-understand flow that is good for a child.
2. Understandably, the author uses made-up names for the topics he is presenting in the book. This is not such a bad idea, to have names that a child will find funny and will be able to remember. However, the author provides almost no way to check what the made-up names are in real life. Not only are there made up names for the math, but also for famous mathematics pioneers that are mentioned. These two things are sometimes confusing and frustrating.
Despite these flaws, the book is very well written and follows in the spirit of Flatland and The Phantom Tollbooth: a magical story about numbers.

The Number Devil is about a young boy who has nightmares in his sleep every night until one night the number devil, who is a low-tempered mathematician, starts to tell him mathematical secrets and tricks for solving even the most compicated problems. This book is filled with famous mathematical problems and theories such as Pascal's triangle, Goldbach's Conjecture, the works of Pythagoras and Arichimedes, and so much more. I found this book incredibly interesting for it's wonderful simplicity towards complicated subjects. Whether you're a kid who wants some further knowledge in math (or just find it interesting) or an adult with mathematical knowledge, you'll find this book an elightening source of enjoyment and knowledge. -C Dubs-

I liked and disliked this book because it was a good way for other kids to learn math and get better at reading at the same time. I also disliked this book because it just didn't interest me a lot. Another reason I liked this book is because it showed you how to work math problems in different ways. It taught me that you can make math fun if you make a game out of it or use food to make fractions. This book is an easy, fun book to read. If you get into the book you will like it. And if you like pretzels you will like this book too. By:Justin

I like the way it made it more fun for me to learn how do to the math skills in this book. This book was good, because it was really better learning a math lesson instead of just opening a math book and studying. It was a very fun way to learn how to do the triangle math skill and all the others. This book has very good pictures to help show how Robert learned from the coconuts and the 1's forest. It showed how the Number Devil was a great teacher to Robert and how he was able to understand everything the Number Devil said and taught. This book made it fun for kids my age to learn math skills. The way we read this book is that we read a chapter everynight. When we came in everyday for class we talked about the math in that chapter and that was our lesson in class. It was more fun that just having a teacher sit in his/her desk and not showing us anything of anyway to work these problems. I learned these things the year beforI didn't understand any of it. Now that I have read the book, I really understand everything a lot better that before.

-Chelsea-

Well, this book was really interesting. It was alright to me, It was different from other books. This book talks about math more than any other books. It will teach you about something that you don't know anything about in math,and you will learn it easier if you do what he teaches you.
Well, not only does the book help with math,it has a lot of metephors. Well it has a lot of funny things in it. The book is really about Robet is having dreams aboout math and the The Number Devil is teaching him. He is learning things that he doesn't understand in school. Every night he has a dream, and it helps him every day he goes to school. At the end his teacher is amazed at what he can do. IF you read this book you will find out what happens.
Epiphany.

THE NUMBER DEVIL WAS A VERY INTERESTING BOOK,IT HELPED ME IN MATH A LOT.AT THE FIRST BEGING OF THE BOOK I DID NOT AT ALL LIKE THE BOOK. IN THE BOOK THEY ALSO TAUGHT ME LANGUAGE.I THINK I WILL GET A VERY GOOD GRADE ON THE BOOK. By.MARKEL