The Number Devil: A Mathematical Adventure

The aim of The Number Devil: A Mathematical Adventure by Hans Magnus Enzensberger with Illustrations by Rotraut Susanne Berner is to make mathematics fun and interesting. The star of the book is a fictional 12-year-old boy named Robert who hates his mathematics class.Robert is visited in his dream for 12 nights, each serving as a chapter to introduce number concepts by The Number Devil, an ingenious mathematical magician who we learn late in the book is named Teplotaxl. The book uses fun easy to remember terms to introduce concepts--for example, Prima Donnas are prime numbers, Hopping is raising a number to a higher power, Hopping backwards is taking the root, while hopping twice is squaring twice. This is not an easy book, but it presents concepts in a thought provoking manner that sparks the interest of those from 12 and above to take the time to learn. Interesting tricks, properties and characteristics of numbers make this worthwhile for the masses. My last Algebra class was in college in 1974. I don't remember most of the concepts. I don't remember the face or name of any of the students in that class or even the Professor; however, I do remember one of the tricks that professor used to spark our interests. While that trick is not in this book it serves to tell you the type things that are in this book. That trick is this. The square of any two digit number ending in 5 will always end in 25. The first digit can be found by multiplying the number by itself and then adding that number to it. For example--25 squared is found by 2 x 2 + 2 = 6 followed by an ending of 25 = 625. Another example is 85 squared = 8 x 8 + 8 ending in 25 = 7225 while 95 squared = 9 x 9 + 9 = 90 with 25 behind it = 9025. While that particular mathematical trick is not in the book, the point is that math presented in the manner of this book and that of my 1974 algebra teacher make learning fun and it will stick with the learner for years to come. I recommend this book to students, parents, teachers and those who enjoy or wish they could enjoy mathematics. Enjoy!

I bought this book based on a recommendation from a math forum. I noticed many reviewers were mentioning how they bought it for young children and thought it would be appropriate for elementary school kids only. I was pleasantly suprised! There are many rich mathematical ideas that can be taken to any level of depth. These topics could easily be talked about in middle school and high school. I'm using it for middle school summer math camp and we will dig into each topic as a number talk. I think it is accessible for multiple levels of students.

This remarkable, clever book will interest almost any kid in a subject that school makes surpassingly boring. Highly recommend for families with children ranging from 8 to 14 years. Adults will love it too!

The Number Devil represents one of the many ways teachers like myself can bring literature into a Mathematics classroom. Pitting the protagonist, Robert, against an “evil” devil representing the toils of Math homework/classwork, the book softens the edges of your traditional Math lecture. This idea of turning Math into an enjoyable, quirky story can have a huge impact on its target audience, Math students of late elementary to middle school classrooms. Robert's attitude immediately forges a connection with students. They (and I) can see Robert's reluctance to cooperate with this Devil (at first) in their own personalities, trudging through every day Math ideas. The real beauty of this book is it's ability to spark enthusiasm and motivation toward learning new ideas. My students can read along the brief chapters, watching Robert's resentment of the Number Devil slowly dissipate, and about midway through, Robert grows eager to complete the Devil's many Mathematical challenges. The ideas presented in the book can easily be transferred into activities for young classes to actively experience Mathematical phenomena for themselves! From the chapter explaining that the number 1 is the basis of every number we can imagine, I've designed a fun activity where my students made mobiles with the number 1 at the top, branching off into each type of number they can imagine (fractions, decimals, tens, hundreds, etc.). I've also recently had my classes create an alphabetical dictionary of the ideas they see pop up in this book. The book takes traditional definitions and manipulates them to a form suitable for kids' enjoyment. This can lead to unbelievable increases in your students' retention of ideas, as they think back to Robert and the Devil, rather than “What did Mr. Price write on the board that day?”. To touch on the book's presentation and functionality, the book is an easy read, with colorful illustrations to disguise the “boring” Math our students may be expecting. The chapters are short and to the point, each introducing a new idea for both Robert and my students to “warm up to”, through playful interactions. I will note some dislikes of mine, primarily stating that the book contains an unfair difficulty spike. It is important to note that when transferring Math into this storybook form, we are far away from a linear textbook, and this uneven learning curve should be expected. Through the course of the book, a class who benefits from the early chapters (counting, infinity, fractions, etc.) may not have a grasp on the later chapters (square roots, geometries, etc.). Likewise, a class who benefits from the deeper final chapters may snooze all the way through the first half of the book. This is a minor complaint, as again, the book is obviously not a replacement for any single grade's curriculum. The book is meant to compliment and “shake up” your coursework to give students more enjoyment toward the subject. It does just that. Harder ideas can simply spark interest in younger readers, while older readers can reflect on what they've already learned and see these ideas in a new lens. In a perfect world this book can be used for nothing else other than motivation, as you may see your students' attitudes transform much like their new identifiable main character Robert's does. Pick up a copy if you're looking for some new ideas for your 4th - 8th graders this school year, don't let your students begin to stigmatize the typical Math classroom at such young ages!

Number theory is an exciting area of math that many schools do not teach, or do not teach enough, because they focus on basic math skills. And, quite often, basic can mean boring, especially for students who have mastered those basic skills. This book (and the game with the same title) presents such concepts as Fibonacci numbers, Pascal's triangle, natural numbers, infinite series, factorials, permutations, and other fun concepts in an interactive and engaging way. I bought this book for my son, and we both reading it and learning (or reviewing, in my case!) a lot of these concepts. The only issue I had with this book (and the game) is that the authors make up some of their own terms instead of using the terms accepted by mathematicians. There are not too many books or games that present math as fun and exciting, and this is one of them. If you have any interest in math (or would like to develop such interest in yourself or your kids), try it! You won't regret it.

The book tells a beautiful story to make children passionate about math! I recommend it!

I'm recently trying to get back into maths and decided to buy this book. It's surely for kids but either I found it really enjoyable and interesting. The author did a good job.

おうち英語や低年齢帰国子女の英語保持界隈では学校で九九が出てきた後かつ受験算数に浸かる前の8歳前後からMurderous Mathsと一緒に手に取る方がいらっしゃるようです、我が家も同じようなタイミングになりました。If You Made A MillionやHow Much Is a Million? （絵本）も同時に楽しんでいます。

This book was absolutely terrible, to the point where it's infuriating to slog through it, but my kids loved it so much that I have to begrudgingly give it five stars. Buy it for your kids if you hate yourself but love them.

Bought for a six year old, as bedtime reading. Three years later, he still re-reads it several times a year and takes it everywhere. It has inspired a love of mathematics in him, and he has become quite the young recreational mathematician. The renamed concepts and words made it easier for him to digest the story first as a work of fiction then, as he re-read it, as an introduction to the fun bits in maths. Wish there were more books like this.