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Kazu No Akuma: Sansū Sūgaku Ga Tanoshikunaru Jūniya
『The Number Devil: A Mathematical Adventure』の邦訳。過去の詰め込み勉強が原因で、数学嫌いになってしまった人はけっこう多いのではないだろうか。本書は、そんな人に向けて書かれた数学の本である。
内容は、数学嫌いの少年ロバートの前に現れた数の悪魔が、毎晩夢の中で数学の魅力を教えるというストーリー。今まで数学アレルギーに悩んでいた人でも、無理なく読み進めていくことができる。
ここで登場するのは素数と無理数、フィボナッチ数、パスカルの三角形、無限と収束、ウソつきのパラドックスなどで、いずれも数学の楽しさを味わうのにぴったりの題材。実生活から離れたものとして数学を捉えていた人に、数学が身近なものだということを教えてくれる。「数学には興味がない」という人にはおすすめの1冊。(土井英司)
内容は、数学嫌いの少年ロバートの前に現れた数の悪魔が、毎晩夢の中で数学の魅力を教えるというストーリー。今まで数学アレルギーに悩んでいた人でも、無理なく読み進めていくことができる。
ここで登場するのは素数と無理数、フィボナッチ数、パスカルの三角形、無限と収束、ウソつきのパラドックスなどで、いずれも数学の楽しさを味わうのにぴったりの題材。実生活から離れたものとして数学を捉えていた人に、数学が身近なものだということを教えてくれる。「数学には興味がない」という人にはおすすめの1冊。(土井英司)
257 pages
First published January 1, 1997
496 people are currently reading
5720 people want to read
About the author
Hans Magnus Enzensberger
310 books166 followersSee also:
Cyrillic: Ханс Магнус Енценсбергер
Hans Magnus Enzensberger was a German author, poet, translator and editor. He had also written under the pseudonym Andreas Thalmayr.
Enzensberger was regarded as one of the literary founding figures of the Federal Republic of Germany and wrote more than 70 books. He was one of the leading authors in the Group 47, and influenced the 1968 West German student movement. He was awarded the Georg Büchner Prize and the Pour Le Mérite, among many others.
He wrote in a sarcastic, ironic tone in many of his poems. For example, the poem "Middle Class Blues" consists of various typicalities of middle class life, with the phrase "we can't complain" repeated several times, and concludes with "what are we waiting for?". Many of his poems also feature themes of civil unrest over economic- and class-based issues. Though primarily a poet and essayist, he also ventured into theatre, film, opera, radio drama, reportage and translation. He wrote novels and several books for children (including The Number Devil, an exploration of mathematics) and was co-author of a book for German as a foreign language, (Die Suche). He often wrote his poems and letters in lower case.
Enzensberger also invented and collaborated in the construction of a machine which automatically composes poems (Landsberger Poesieautomat). This was used during the 2006 Football World Cup to commentate on games.
Tumult, written in 2014, is an autobiographical reflection of his 1960s as a left-wing sympathizer in the Soviet Union and Cuba.
Enzensberger translated Adam Zagajewski, Lars Gustafsson, Pablo Neruda, W. H. Auden and César Vallejo. His own work has been translated into more than 40 languages.
Cyrillic: Ханс Магнус Енценсбергер
Hans Magnus Enzensberger was a German author, poet, translator and editor. He had also written under the pseudonym Andreas Thalmayr.
Enzensberger was regarded as one of the literary founding figures of the Federal Republic of Germany and wrote more than 70 books. He was one of the leading authors in the Group 47, and influenced the 1968 West German student movement. He was awarded the Georg Büchner Prize and the Pour Le Mérite, among many others.
He wrote in a sarcastic, ironic tone in many of his poems. For example, the poem "Middle Class Blues" consists of various typicalities of middle class life, with the phrase "we can't complain" repeated several times, and concludes with "what are we waiting for?". Many of his poems also feature themes of civil unrest over economic- and class-based issues. Though primarily a poet and essayist, he also ventured into theatre, film, opera, radio drama, reportage and translation. He wrote novels and several books for children (including The Number Devil, an exploration of mathematics) and was co-author of a book for German as a foreign language, (Die Suche). He often wrote his poems and letters in lower case.
Enzensberger also invented and collaborated in the construction of a machine which automatically composes poems (Landsberger Poesieautomat). This was used during the 2006 Football World Cup to commentate on games.
Tumult, written in 2014, is an autobiographical reflection of his 1960s as a left-wing sympathizer in the Soviet Union and Cuba.
Enzensberger translated Adam Zagajewski, Lars Gustafsson, Pablo Neruda, W. H. Auden and César Vallejo. His own work has been translated into more than 40 languages.
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Displaying 1 - 30 of 789 reviews
October 7, 2012
I love the idea of a novel that relies on and promotes interest in math, but the execution here just fell way short for me. The story itself - that a boy who hates math learns to like it through a series of dreams in which he interacts with a Number Devil - is a little thin and repetitive. But what I found bothered me the most were the explanations of the math concepts. I've seen some great nonfiction books that make math concepts interesting AND explain them in multiple ways for students who catch on differently. This book would introduce a concept, state some random things you could do with it (but usually not why you might want to), and move on without trying to address WHY something was the way it was, or multiple learning styles. Another thing I couldn't totally get on board with was renaming math concepts. I get that some of the terms might have been easier to remember, but the real name for them is never mentioned, so kids might come away knowing all about "prima donna numbers" and never put together that they're really called prime numbers. And some seemed unnecessary - is "Bonacci numbers" really that much easier to remember than "Fibonacci numbers"? I just had such high hopes for this one and came away disappointed.
October 10, 2025
A boy named Robert falls asleep expecting the usual nonsense, sliding down endless slides, getting swallowed by fish, that kind of humiliation. Instead, he gets a grasshopper-sized old man who insists he’s the Number Devil. The Devil says numbers are simple, infinite, and everywhere. Robert doesn’t buy it. Then again, he’s dreaming, so what can he do?
The Devil shows up again, perched on a mushroom like he’s auditioning for Alice in Wonderland. The topic is zero. The Romans didn’t have it, which is why their numbers looked like a drunk carved them in marble. Zero makes hopping numbers possible, ten hopping once is ten, hopping twice is a hundred, hopping thrice is a thousand. Suddenly Robert realizes numbers don’t just sit there; they jump around like frogs.
Then come the party trick numbers. Ones lined up in rows, squared against themselves, blooming into palindromes. 11 × 11 = 121. 111 × 111 = 12321. 1111 × 1111 = 1234321. Each step adds a digit, each product folds in on itself like a mirror. Robert watches the sequence stretch out in the sky, neat as origami, numbers turning symmetrical just because they can.
They’re in a cave. The Devil is cranky. Robert learns about prime numbers, which the Devil calls “prima donnas.” They’re the celebrities of arithmetic: un-divisible, temperamental, and impossible to predict. Mathematicians spend lifetimes chasing them down. Robert isn’t sure why anyone would bother, but he admires the lunacy of it.
They land on a beach. The Devil conjures up a calculator the size of a couch. Robert discovers fractions that never end, decimals that spin forever, and irrational numbers that refuse to play by the rules. He hates it, then loves it, then hates it again. The Devil smirks and waves his stick, filling the sky with endless nines. Robert begs for mercy.
Now it’s coconuts falling into neat little triangles in the sand. Robert counts them and sees triangular numbers, neat little sums stacked into pyramids. Add them in pairs and they turn into perfect squares. The Devil is delighted. Robert just wants a swim. He gets one, but the pool is full of numbers. Naturally.
A potato field. Don’t ask why. Fibonacci (here called Bonacci) numbers sprout like weeds. One plus one is two, two plus one is three, three plus two is five, and suddenly you’ve got rabbits breeding all over the place. Robert discovers that nature cheats at math: spirals in shells, seeds in sunflowers, everything obeying the Bonacci gospel.
Robert is introduced to factorials. Arrangements. Combinations. How many ways can you line up potatoes, or socks, or people? Answer: more ways than you’ll ever need. Numbers grow like weeds when you multiply them this way. Robert feels both small and dizzy.
Now it’s infinity’s turn. The Devil proves you can slice it, stretch it, rearrange it, and it still won’t die. Robert thinks it’s unfair. The Devil shrugs: that’s math for you.
The Devil scribbles Pascal’s Triangle in the air. It’s like a family tree of numbers, except it actually makes sense. Robert sees patterns he never imagined, and the Devil tells him these patterns explain dice, cards, and probably the lottery, though not in any way useful.
Circles. Pi. Numbers that never repeat, never end. Robert stares at the digits until his brain aches. The Devil insists this is beauty. Robert suspects it’s torture dressed up in Greek letters.
Imaginary numbers. The Devil drops the bomb: √-1. Robert thinks it’s a joke. It isn’t. Math, apparently, survives on things that don’t exist. Robert feels like the floor just gave way beneath him. The Devil cackles.
Robert is ushered into Number Heaven, where famous mathematicians mumble formulas like drunks at last call. The Devil, whose real name is Teplotaxl, reveals he’s just one of many. Robert, the kid who hated math homework, gets invited to join the club. He wakes up different. He may still hate his teacher, but numbers no longer scare him. They’re alive. They’re ridiculous. They’re infinite.
If you ever thought math was sterile and joyless, this book is the antidote. It’s funny, strange, and quietly subversive; teaching you about numbers without ever feeling like school. You end up learning a lot, almost by accident, and you laugh while you’re at it. That’s a good bargain.
The Devil shows up again, perched on a mushroom like he’s auditioning for Alice in Wonderland. The topic is zero. The Romans didn’t have it, which is why their numbers looked like a drunk carved them in marble. Zero makes hopping numbers possible, ten hopping once is ten, hopping twice is a hundred, hopping thrice is a thousand. Suddenly Robert realizes numbers don’t just sit there; they jump around like frogs.
Then come the party trick numbers. Ones lined up in rows, squared against themselves, blooming into palindromes. 11 × 11 = 121. 111 × 111 = 12321. 1111 × 1111 = 1234321. Each step adds a digit, each product folds in on itself like a mirror. Robert watches the sequence stretch out in the sky, neat as origami, numbers turning symmetrical just because they can.
They’re in a cave. The Devil is cranky. Robert learns about prime numbers, which the Devil calls “prima donnas.” They’re the celebrities of arithmetic: un-divisible, temperamental, and impossible to predict. Mathematicians spend lifetimes chasing them down. Robert isn’t sure why anyone would bother, but he admires the lunacy of it.
They land on a beach. The Devil conjures up a calculator the size of a couch. Robert discovers fractions that never end, decimals that spin forever, and irrational numbers that refuse to play by the rules. He hates it, then loves it, then hates it again. The Devil smirks and waves his stick, filling the sky with endless nines. Robert begs for mercy.
Now it’s coconuts falling into neat little triangles in the sand. Robert counts them and sees triangular numbers, neat little sums stacked into pyramids. Add them in pairs and they turn into perfect squares. The Devil is delighted. Robert just wants a swim. He gets one, but the pool is full of numbers. Naturally.
A potato field. Don’t ask why. Fibonacci (here called Bonacci) numbers sprout like weeds. One plus one is two, two plus one is three, three plus two is five, and suddenly you’ve got rabbits breeding all over the place. Robert discovers that nature cheats at math: spirals in shells, seeds in sunflowers, everything obeying the Bonacci gospel.
Robert is introduced to factorials. Arrangements. Combinations. How many ways can you line up potatoes, or socks, or people? Answer: more ways than you’ll ever need. Numbers grow like weeds when you multiply them this way. Robert feels both small and dizzy.
Now it’s infinity’s turn. The Devil proves you can slice it, stretch it, rearrange it, and it still won’t die. Robert thinks it’s unfair. The Devil shrugs: that’s math for you.
The Devil scribbles Pascal’s Triangle in the air. It’s like a family tree of numbers, except it actually makes sense. Robert sees patterns he never imagined, and the Devil tells him these patterns explain dice, cards, and probably the lottery, though not in any way useful.
Circles. Pi. Numbers that never repeat, never end. Robert stares at the digits until his brain aches. The Devil insists this is beauty. Robert suspects it’s torture dressed up in Greek letters.
Imaginary numbers. The Devil drops the bomb: √-1. Robert thinks it’s a joke. It isn’t. Math, apparently, survives on things that don’t exist. Robert feels like the floor just gave way beneath him. The Devil cackles.
Robert is ushered into Number Heaven, where famous mathematicians mumble formulas like drunks at last call. The Devil, whose real name is Teplotaxl, reveals he’s just one of many. Robert, the kid who hated math homework, gets invited to join the club. He wakes up different. He may still hate his teacher, but numbers no longer scare him. They’re alive. They’re ridiculous. They’re infinite.
If you ever thought math was sterile and joyless, this book is the antidote. It’s funny, strange, and quietly subversive; teaching you about numbers without ever feeling like school. You end up learning a lot, almost by accident, and you laugh while you’re at it. That’s a good bargain.
February 24, 2016
This book makes maths fun, even for those little people who believe it to be a laborious trudge through treacle. In fact, that would describe Robert, the main character in this book. He has been struggling with maths for as long as he can remember. One night, he dreams that he meets a little devil, The Number Devil, who teaches him, as he sleeps, all sorts of useful tricks with numbers.
When you enjoy something, and gain immediate benefit, you obviously learn more.
My Dad made all aspects of mathematics enjoyable for me from a very early age, almost from when I could walk and talk, by relating what we were seeing in the real world to mathematics in some way. He didn't label the principles as geometry, algebra, arithmetic, and so on. He just mde it all part of my world. Consquently, I never scored less than 90% in any maths test or exam in my life. I just enjoy maths as much as living.
The same holds for Robert, and for readers of this lovely little book.
My grandson was hating maths, and couldn't see the point. When I took him through the first chapter of The Number Devil, he could suddenly, and effortlessly, multiply 11 by 11, 1111 by 1111, 1111111 by 1111111 and so on. He also learned, through self motivation inspired by his "new trick" to multiply any number you could throw at him by eleven.
This may seem a small step, but you can believe me when I tell you that it was a massive step for Alfie. Furthermore, he couldn't wait to get to school the next day to show his new skills to his class-mates and his teacher.
That wasn't all. There was much more magic to be revealed in this great little book, and I would encourage anyone to share it with their children, even if they are already very numerate. It just gives them, and you, a new spin on an ancient subject.
When you enjoy something, and gain immediate benefit, you obviously learn more.
My Dad made all aspects of mathematics enjoyable for me from a very early age, almost from when I could walk and talk, by relating what we were seeing in the real world to mathematics in some way. He didn't label the principles as geometry, algebra, arithmetic, and so on. He just mde it all part of my world. Consquently, I never scored less than 90% in any maths test or exam in my life. I just enjoy maths as much as living.
The same holds for Robert, and for readers of this lovely little book.
My grandson was hating maths, and couldn't see the point. When I took him through the first chapter of The Number Devil, he could suddenly, and effortlessly, multiply 11 by 11, 1111 by 1111, 1111111 by 1111111 and so on. He also learned, through self motivation inspired by his "new trick" to multiply any number you could throw at him by eleven.
This may seem a small step, but you can believe me when I tell you that it was a massive step for Alfie. Furthermore, he couldn't wait to get to school the next day to show his new skills to his class-mates and his teacher.
That wasn't all. There was much more magic to be revealed in this great little book, and I would encourage anyone to share it with their children, even if they are already very numerate. It just gives them, and you, a new spin on an ancient subject.
October 6, 2017
letto perché di me si potesse dire: nulla lasciò intentato.
peccato per il corollario: ogni tentativo fu vano.
peccato per il corollario: ogni tentativo fu vano.
December 8, 2014
This book was by far the most interesting book I have read in years. I found it really interesting as the concepts in mathematics were very interesting, yet explained in simple terms. This book teaches you about mathematics in general, like the fact that some properties of numbers can help you in solving problems. I rated this book five stars because of the complexity in such a simple bedtime story. I would recommend this book to anyone who likes math, but I’d also reccomend this book to someone who doesn’t like math as well, as this book teaches you about math without you having to struggle. The Number Devil is one of the best books I have ever read, the story is easy to follow and it really makes you think. I enjoyed this book myself because I love learning new concepts as well as how they make sense in the real world.
January 1, 2012
Imagine that a math teacher wanted to write a children's book to show kids how cool math really was; but since it's a math teacher and not an English teacher doing the writing, all you end up with are math concepts written out in analogies similar to what you'd hear in a math classroom -- that's what this book is like. The story is about a boy named Robert who hates his math class and math teacher and by extension math in general. He falls asleep and over a series of twelve different dreams over twelve different nights, he learns about different math concepts from a dream guide who calls himself a Number Devil. The devil presents math concepts in kid-friendly terms and even uses kid-friendly language to describe them. For example, instead of using the term exponents, the devil uses the term "hopping"; he also calls prime numbers prima donna numbers. And obvious spoiler, but Robert comes to appreciate math by the end of the book. My first criticism is that half of the number concepts aren't described as cleverly as prima donna numbers. Calling Fibonacci numbers Bonacci numbers or Pascal's Triangle a Numbers Triangle is simply lazy. My second and bigger criticism is that the prose is terrible. The dialogue between Robert and the devil reads far less like a boy talking to a dream figure, and more like a math teacher talking to an imaginary student who is engaged in his lesson. I like math and find it fascinating, but this book irritated me more than made me appreciate numbers. I'm sure math teachers are massive fans of this book; I was not.
October 28, 2015
Random math thinly disguised as a novel. I get what it's trying to do but it feels more like the kind of characters that kids' textbooks have to make the info more "fun." there isn't a plot here. But if it gets kid's reading about math then go go go. Plus, the illustrations are really cute.
November 20, 2019
Romanzo graziosissimo che racconta in modo semplice, intelligente e divertente alcuni concetti matematici di base (ma non solo). Col pretesto dei sogni/incubi di Roberto, viene introdotto il Mago della Matematica che, con i suoi trucchi, spiega alcune regole e formule con esempi di facile comprensione per grandi e piccini. Consigliato per chi si deve riconciliare con questa materia un po' ostica
This entire review has been hidden because of spoilers.
February 23, 2015
Great book.
It talks about maths in a way that is as simple as 1+1=2.
I was way behind in maths going into high school, and I have learnt so much from this book in 1-2 months.
I learnt stuff like Fractions, Bonacci/Fibonacci numbers, Decimals, Factorial (Vroom!), Hopping numbers, Prima Donnas, and Triangle numbers.
My favorite was the "Hopping Numbers". I spent a good part of a day just writing them all down. I wrote down 55 hopping numbers, and the biggest one I did was 18,014,398,509,481,984, which was too big for my calculator to check.
"All Englishmen are liars," the man mumbled, "but if I say it, what then? I'm an Englishman myself. so I'm lying too. But then what I've just said - namely, that all Englishmen are liars - is not true. but if Englishmen tell the truth, then what I said before must be true as well. In other words, we are liars."
A must read book. :D
First 55 Hopping numbers:
1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 8192, 16384, 32768, 65536, 131072, 262144, 524288, 1048576, 2097152, 4194304, 8388608, 16777216, 33554432, 67108864, 13427728, 268435456, 67108864, 13427728, 268435456, 536870912, 1073741824, 4294967296, 8589934592, 17179869184, 34359738368, 68719476736, 137438953472, 274877906944, 549755813888, 1099511627776, 2199023255552, 439846511104, 8796093022208, 17592186044416, 35184372088832, 70368744177664, 562949953421312, 1125899906842624, 2251799813685248, 4503599627370496, 9007199254740992, 18014398509481984.
It talks about maths in a way that is as simple as 1+1=2.
I was way behind in maths going into high school, and I have learnt so much from this book in 1-2 months.
I learnt stuff like Fractions, Bonacci/Fibonacci numbers, Decimals, Factorial (Vroom!), Hopping numbers, Prima Donnas, and Triangle numbers.
My favorite was the "Hopping Numbers". I spent a good part of a day just writing them all down. I wrote down 55 hopping numbers, and the biggest one I did was 18,014,398,509,481,984, which was too big for my calculator to check.
"All Englishmen are liars," the man mumbled, "but if I say it, what then? I'm an Englishman myself. so I'm lying too. But then what I've just said - namely, that all Englishmen are liars - is not true. but if Englishmen tell the truth, then what I said before must be true as well. In other words, we are liars."
A must read book. :D
First 55 Hopping numbers:
1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 8192, 16384, 32768, 65536, 131072, 262144, 524288, 1048576, 2097152, 4194304, 8388608, 16777216, 33554432, 67108864, 13427728, 268435456, 67108864, 13427728, 268435456, 536870912, 1073741824, 4294967296, 8589934592, 17179869184, 34359738368, 68719476736, 137438953472, 274877906944, 549755813888, 1099511627776, 2199023255552, 439846511104, 8796093022208, 17592186044416, 35184372088832, 70368744177664, 562949953421312, 1125899906842624, 2251799813685248, 4503599627370496, 9007199254740992, 18014398509481984.
January 25, 2019
January 8, 2019 -
4 Stars
I read this with my grade six students. They figured out the problems as we went. The story/plot itself was kind of boring but I enjoyed the problems and the student solving them.
4 Stars
I read this with my grade six students. They figured out the problems as we went. The story/plot itself was kind of boring but I enjoyed the problems and the student solving them.
April 26, 2015
خیلی کتاب خوبی بود. اگه ریاضیات و بازی با اعداد و این تیپ چیزها رو دوست دارین بخونیدش. مخصوصا برای نوجوانها عالیه. دنیای زیبایی رو براشون از اعداد به تصویر می کشه و به شیوه شیرینی بهشون اطلاعات می ده در مورد علم اعداد و ریاضیات.
با اینکه از سن من گذشته بود وقتی خوندمش ، ازش خیلی لذت بردم!
با اینکه از سن من گذشته بود وقتی خوندمش ، ازش خیلی لذت بردم!
April 6, 2013
...But as he stood in front of his mirror in his pajamas, brushing his teeth, he felt something tickling his chest and looked down to see a tiny five-pointed star on a thin golden chain. He couldn't believe his eyes. This time his dream had come true! ...After he'd dressed, he took the chain off and stuck it in his pocket: he didn't want his mother asking silly questions. ...Where'd that star come from? she'd want to know the minute she saw it. Boys don't wear jewelry! ...How could he tell her it was the emblem of a secret order?
Perhaps a mathematical fairytale (yes! what a truly delectable combo) is a dubious inclusion in a round-up of the golden ratio in literature. Does a story in which the purpose is clearly didactic and in which the emphasis is on the exposition of the nifty niceties of various numerical patterns really qualify as literature? Isn't a mathematics text thinly disguised as a children's story a bit suspect?
In its defence, I have to say that The Number Devil does have the three essential C's of a story - character, conflict and context - so I'm giving it the benefit of the doubt. The plot, moreover, floats as lightly as a feather on a froth of allusions to some truly great tales told by (or about) mathematicians down the ages: the mushrooms of Alice in Wonderland* make an appearance, the cave of Plato** is the setting for one of Robert's dreams, the anecdote about the schoolmaster and young Karl Gauss***is re-enacted by Robert and Mr. Boekel, and the great mathematical mystery which plagued medieval theologians - 'How many angels can dance on the point of a pin?' - is restated in a new guise.
Ahhh, what a glorious book! But I didn't give it five stars just because I love mathematics and fairytales. I did it because it made a point I've never ever seen elsewhere.
Robert, the young dreamer of The Number Devil, has a problem with mathematics. He hates it.
His teacher, the pretzel-loving Mr. Boekel, is apt to ask such sinister questions as: 'If 2 pretzel makers can make 444 pretzels in 6 hours, how long does it take 5 pretzel makers to make 88 pretzels?' Fortunately for Robert and his mathematical future, his dreams are invaded by a chirpy little chap who introduces himself as 'the number devil'.
Starting with the number one and its properties, the number devil explores different facets of the realm of mathematics. Robert, despite his initial antagonism, becomes increasingly intrigued. The sixth night of dreaming is devoted to Mr. Bonacci and his rabbit clock (a peculiar eared device where the markings correspond to months rather than hours), while the tenth night of dreaming is devoted to the golden ratio.
On that night, the number devil re-introduces the Fibonacci numbers of the sixth night, much to Robert's disgust ('You and your Bonacci!' he exclaims. 'Tell me, is that guy your best friend or something?') and shows him how the golden ratio is hidden in the sequence.
Enzensberger has made an interesting observation at this point - and this is what made me decide to include The Number Devil in my catalogue of the golden ratio in literature and to give it five stars. I don't know of anyone else who has actually bothered to point out that it's not just the Fibonacci sequence which turns up the golden ratio. Pick any two numbers (Robert chooses 11 and 17) and use them as the basis of a Fibonacci-like additive sequence: add them together, then add the last number to the total to make a new term and keep on doing this for as long as you please. Pretty soon, the ratio of those last two numbers is going to tend towards the golden ratio, no matter what initial numbers you chose.
'Is it buried in all numbers?' Robert asks.
'It is,' said the number devil.
At the end of the book, Robert is awarded the Order of Pythagoras (Fifth Class) - and is given a gold star on a chain. As ever in The Number Devil, no reference is made to the historical precedent, no explanation is given about the allusion. The five-pointed gold star is, however, the symbol of the Pythagorean Brotherhood and Robert is right in thinking of it as the emblem of a secret order. It was exactly that: the pentagram was called 'the number of man' and was the device by which members recognised each other.
The Number Devil is a delightful book, where even the most whimsical incidents are drawn from the history of mathematics. I caught quite a few of the allusions, but I suspect just as many went over my head. While there's an extra dimension of pleasure in recognising those hidden references, the book is truly enjoyable anyway. I hope it becomes a modern classic. It certainly deserves just such an accolade.
* Alice in Wonderland was written by the mathematician and theologian, Rev. Charles Lutwidge Dodgson under the pseudonym, Lewis Carroll. The famous answer - 'forty-two' - to the question in The Hitchhiker's Guide to the Galaxy 'What is the answer to life, the universe and everything?' is taken from Alice Through the Looking Glass.
** Pythagoras was admired by Plato who used some of his ideas (particularly in what is called the geometry of the 'Platonic solids').
*** The incident at the very end of The Number Devil is similar to a story told of Karl Gauss. The boy, later to become 'The Prince of Mathematicians', was in a class asked by the teacher to add up all the numbers from 1 to 100. Almost at once, Gauss had the correct answer (not a calculator in sight either!). He used the same technique Robert uses to work out the answer.
May 26, 2025
Ammetto di averlo letto fuori tempo massimo. Forse, verso i dodici-tredici anni, avrebbe davvero fatto il suo lavoro.
Difficile invece, a trentasei, apprezzare la matematica attraverso questo libro, anche se la parte della disciplina qui affrontata mi è sempre piaciuta e mi affascina tuttora; e a dire il vero, era pure quella che un po' mi salvava dalla stupidità.
Perché l'ho letto? Una collega coraggiosa me lo ha consigliato.
Mi è piaciuto? Sì; con le riserve di cui sopra, che non sono colpa del libro e né del suo autore, che naturalmente si rivolge a un altro pubblico, per quanto lo si possa comprendere e apprezzare pure da adulti; specie se il conflitto con la matematica, come nel mio caso, non si è ancora del tutto risolto.
Difficile invece, a trentasei, apprezzare la matematica attraverso questo libro, anche se la parte della disciplina qui affrontata mi è sempre piaciuta e mi affascina tuttora; e a dire il vero, era pure quella che un po' mi salvava dalla stupidità.
Perché l'ho letto? Una collega coraggiosa me lo ha consigliato.
Mi è piaciuto? Sì; con le riserve di cui sopra, che non sono colpa del libro e né del suo autore, che naturalmente si rivolge a un altro pubblico, per quanto lo si possa comprendere e apprezzare pure da adulti; specie se il conflitto con la matematica, come nel mio caso, non si è ancora del tutto risolto.
June 18, 2017
This book was a lot of fun. I'm a big fan of Flatland, so I enjoy anytime math can be turned into a story. This book doesn't have a ton of story, but just enough to make it a page turner. Robert's math teacher, Mr. Bockel doesn't seem to be a very inspiring educator, doing little else but assigning word problems while surreptitiously munching on pretzels. Robert thinks math is confusing and boring. All that changes when his dreams are visited by a strange genie-like character called The Number Devil. Through the course of many visits to The Number Devil's mathematical dreamscape, Robert learns that not only does math make a lot of sense, but it's actually pretty interesting.
The Number Devil gives mathematical concepts silly names, calling prime numbers "prima donna numbers" and exponents "hopping numbers," which could be confusing, but there's a guide at the end of the book which explains what everything is really called. I actually think not using the "correct" names might make the book more accessible to kids. Robert has the chance to meet other "number devils," mathematicians from throughout history, and asks why more of them aren't women. It's a great questions, and though the book doesn't delve into that issue too deeply, it's nice to see it addressed.
The Number Devil gives mathematical concepts silly names, calling prime numbers "prima donna numbers" and exponents "hopping numbers," which could be confusing, but there's a guide at the end of the book which explains what everything is really called. I actually think not using the "correct" names might make the book more accessible to kids. Robert has the chance to meet other "number devils," mathematicians from throughout history, and asks why more of them aren't women. It's a great questions, and though the book doesn't delve into that issue too deeply, it's nice to see it addressed.
February 29, 2016
This book told as a 12 nights dream of a child with a mathematical devil is a serious attempt to prove that mathematics can be entertaining,interesting,beautiful and fun and not a boring,useless,ugly and hermetic subject.
It is aimed mainly to young teens,but is also enjoyable by adults that for some reason hate the maths or have a wrong concept of this field.
Is a tale where departing of elemental concepts as natural numbers,prime numbers,powers and square roots introduce more advanced concepts as triangular numbers,Pascal triangle and his properties,permutations,combinations,properties of numerable sets of numbers,convergence of power series,divergence of armonic series and a introduction to topological results as the Euler characteristic of a graph and a poliedre and the Klein bottle ending with reflections of the idea of mathematical demostration and a brief decription of the greatest mathematicians.
It has no demostrations ,only expositions of concepts and results.
All are explained with a simple language and clear and beautiful drawings
It is aimed mainly to young teens,but is also enjoyable by adults that for some reason hate the maths or have a wrong concept of this field.
Is a tale where departing of elemental concepts as natural numbers,prime numbers,powers and square roots introduce more advanced concepts as triangular numbers,Pascal triangle and his properties,permutations,combinations,properties of numerable sets of numbers,convergence of power series,divergence of armonic series and a introduction to topological results as the Euler characteristic of a graph and a poliedre and the Klein bottle ending with reflections of the idea of mathematical demostration and a brief decription of the greatest mathematicians.
It has no demostrations ,only expositions of concepts and results.
All are explained with a simple language and clear and beautiful drawings
June 8, 2016
هذا كتاب لطيف خفيف وأحببته حقاً.
العفرتة إن كانت فستكون في الرياضيات، كتاب يحرّك العقل بسحر الأرقام.
قصة روبرت مع عفريت الأرقام الذي يحبّب له مادة الرياضيات بطرقه العجائبية.
مجرد عمليات حسابية بسيطة ستقودك إلى عوالم داخل الأرقام تجعلك تدور وتدور وتدور.
أراه متوسط الجودة للأطفال، وفائق الروعة لمن هم على الأقل يحبون الرياضيات ولو من بعيد.
بالنسبة لي، استمتعت بكل جزئية فيه، وعلمت أشياء لم أكن أعرفها قبل قراءتي للكتاب رغم ممارساتي وحبي للرياضيات، والحساب
June 19, 2018
خلاصه:
رابرت (مثل خیلی از بچههای دیگر) از ریاضی متنفر است. او که مدام خوابها و کابوسهای عجیبی میبیند، در یکی از این خوابها با موجود شگفتانگیزی مواجه میشود که خودش را عدد شیطان مینامد. او و عدد شیطان به مدت دوازده شب به قلمروهای زیبا و جذاب ریاضی سرک میکشند: اعداد اول، سریهای فیبوناچی، اعداد مثلثی، ترکیبیات و...
درباره کتاب:
یکی از فرقهای ریاضی با علوم دیگر انتزاعی بودن آن است. برای همین علیرغم کتابهای جذاب زیادی که مختص کودکان و نوجوانان نوشته شدهاند، کتابهای کمتری میبینید که با این نیت نوشته شده باشند که کودکان را با ریاضی آشتی بدهند (برای نمونه میتوانید این را ببینید). عد شیطان قطعا در ماموریتی که برای خودش در نظر گرفته است موفق شدهاست:
*سطح مطالب بیانشده طوری در نظر گرفته شدهاست که تقریبا برای تمام بچههای پنجم دبستان به بالا قابل فهم است؛
*این کتاب داستان دارد! یعنی اینطور نیست که صرفا یکسری مفهوم ریاضی را به صورت قصهوار به هم چسبانده باشد؛
*مفاهیم ریاضی مطرح شده واقعا دستچین شدهاند: هم جذابند، هم در محیط اطراف قابل مشاهدهاند و هم کودک می تواند پس از چند قدم جلو جلو برای خودش خواصی را کشف کند؛
*با مشارکت دادن شخصیت اصلی (و به تبع آن مخاطب) در اکتشافات به کودکان اعتماد به نفس میدهد؛
*حالتی رازآمیز برای کودک ایجاد میکند که باعث میشود فکر کند به اطلاعاتی سری و ارزشمند دست یافتهاست.
نکات:
کلا یکی از جذابترین تجربههای کتابخوانی من در دوران دبستان و راهنمایی بود.
نیاز به دانش اولیهٔ ریاضی در حد ریاضیات سوم-چهارم دبستان زمان ما دارد!
چندین بار هم بدون هیچ بار ایدئولوژیکی از لفظ شیطان (یا در بعضی ترجمهها جن!) استفاده شده.
http://davanevis.blog.ir/post/number-...
رابرت (مثل خیلی از بچههای دیگر) از ریاضی متنفر است. او که مدام خوابها و کابوسهای عجیبی میبیند، در یکی از این خوابها با موجود شگفتانگیزی مواجه میشود که خودش را عدد شیطان مینامد. او و عدد شیطان به مدت دوازده شب به قلمروهای زیبا و جذاب ریاضی سرک میکشند: اعداد اول، سریهای فیبوناچی، اعداد مثلثی، ترکیبیات و...
درباره کتاب:
یکی از فرقهای ریاضی با علوم دیگر انتزاعی بودن آن است. برای همین علیرغم کتابهای جذاب زیادی که مختص کودکان و نوجوانان نوشته شدهاند، کتابهای کمتری میبینید که با این نیت نوشته شده باشند که کودکان را با ریاضی آشتی بدهند (برای نمونه میتوانید این را ببینید). عد شیطان قطعا در ماموریتی که برای خودش در نظر گرفته است موفق شدهاست:
*سطح مطالب بیانشده طوری در نظر گرفته شدهاست که تقریبا برای تمام بچههای پنجم دبستان به بالا قابل فهم است؛
*این کتاب داستان دارد! یعنی اینطور نیست که صرفا یکسری مفهوم ریاضی را به صورت قصهوار به هم چسبانده باشد؛
*مفاهیم ریاضی مطرح شده واقعا دستچین شدهاند: هم جذابند، هم در محیط اطراف قابل مشاهدهاند و هم کودک می تواند پس از چند قدم جلو جلو برای خودش خواصی را کشف کند؛
*با مشارکت دادن شخصیت اصلی (و به تبع آن مخاطب) در اکتشافات به کودکان اعتماد به نفس میدهد؛
*حالتی رازآمیز برای کودک ایجاد میکند که باعث میشود فکر کند به اطلاعاتی سری و ارزشمند دست یافتهاست.
نکات:
کلا یکی از جذابترین تجربههای کتابخوانی من در دوران دبستان و راهنمایی بود.
نیاز به دانش اولیهٔ ریاضی در حد ریاضیات سوم-چهارم دبستان زمان ما دارد!
چندین بار هم بدون هیچ بار ایدئولوژیکی از لفظ شیطان (یا در بعضی ترجمهها جن!) استفاده شده.
http://davanevis.blog.ir/post/number-...
April 23, 2014
This book is a thinly veiled novelization of a few math problems. It's wrapped in a story about a boy with crazy dreams that begins dreaming about math and learning things from a number devil.
My impression was that the book got the formula all wrong. The story is nonsensical and tedious, so you're ready to get to the math. The math is then explained via conversation between the main character and the number devil, so you really have to reflect on the topics after each chapter to understand them. You could easily read through the book and learn nothing but the overall story.
The worst offense of this book is the made up names for mathematical terms. They have a warning at the end of the book telling readers that they should listen to their teacher and use the proper name instead of the dream term. If you want me to use the correct term, don't teach me the wrong term! For example, they refer to prime numbers as prima donnas, the Fibonacci sequence as Bonacci numbers, and 4! (four factorial) as four vroom!
As somebody that already knows the mathematical concepts, this book was a big disappointment. Unless it really grabs a kid's attention, I don't see how this book would be a preferred way of teaching math concepts - it takes longer than an explanation and example of the topic, the explanation gets muddled down, and it teaches the wrong terms.
My impression was that the book got the formula all wrong. The story is nonsensical and tedious, so you're ready to get to the math. The math is then explained via conversation between the main character and the number devil, so you really have to reflect on the topics after each chapter to understand them. You could easily read through the book and learn nothing but the overall story.
The worst offense of this book is the made up names for mathematical terms. They have a warning at the end of the book telling readers that they should listen to their teacher and use the proper name instead of the dream term. If you want me to use the correct term, don't teach me the wrong term! For example, they refer to prime numbers as prima donnas, the Fibonacci sequence as Bonacci numbers, and 4! (four factorial) as four vroom!
As somebody that already knows the mathematical concepts, this book was a big disappointment. Unless it really grabs a kid's attention, I don't see how this book would be a preferred way of teaching math concepts - it takes longer than an explanation and example of the topic, the explanation gets muddled down, and it teaches the wrong terms.
February 6, 2015
https://30dediferencia.wordpress.com/...
No creo que leer El diablo de los libros pueda hacer que un niño al que no le gusten las matemáticas empieza a apreciarlas, pero estoy convencido de que no era esa la intención del autor al escribir el libro, sino más bien crear una historia entretenida con las matemáticas como hilo argumental en la que se nos muestran curiosidades y aspectos llamativos de las mismas que puedan despertar posteriormente el interés de los chavales.
Me ha resultado muy curiosa la licencia que se toma el autor de cambiar algunos términos matemáticos, como la serie de Fibonacci, las raíces cuadradas, las potencias o los factoriales y aunque entiendo que algún purista pueda sentirse molesto al final del libro encontramos las explicaciones precisas y tampoco hay que darle más importancia de la que tiene.
En resumen una historia entretenida, quizás algo tediosa en algunos momentos porque quizás uno esperara un poquito más de acción, y que puede estar bien para chavales a partir de 10-11 años que quieran encontrar cosas curiosas en el mundo de las mates.
No creo que leer El diablo de los libros pueda hacer que un niño al que no le gusten las matemáticas empieza a apreciarlas, pero estoy convencido de que no era esa la intención del autor al escribir el libro, sino más bien crear una historia entretenida con las matemáticas como hilo argumental en la que se nos muestran curiosidades y aspectos llamativos de las mismas que puedan despertar posteriormente el interés de los chavales.
Me ha resultado muy curiosa la licencia que se toma el autor de cambiar algunos términos matemáticos, como la serie de Fibonacci, las raíces cuadradas, las potencias o los factoriales y aunque entiendo que algún purista pueda sentirse molesto al final del libro encontramos las explicaciones precisas y tampoco hay que darle más importancia de la que tiene.
En resumen una historia entretenida, quizás algo tediosa en algunos momentos porque quizás uno esperara un poquito más de acción, y que puede estar bien para chavales a partir de 10-11 años que quieran encontrar cosas curiosas en el mundo de las mates.
April 8, 2018
Well, that was interestingly cute... like if you took math class in Wonderland or if you studied math on drugs, or something, but I cannot deny it was great.
Honestly, I don’t think this book will make you better at math, however it may help you understand some complex theoretical concepts, since it doesn’t focus in the applied mathematics, but rather in the pure theory behind them.
The narration is fantastic and creative, and in fact, pretty attractive. Besides, the pictures and dares really complement the story. So whether you struggle with math or not, I would recommend to read this book. :)
P.S. I believe that the fact that the math geniuses are portrayed as devils is a pretty straight forward message... I mean, there’s math hell!! I know maths are mischievous and devilish, but this is literally saying *maths are hell*, isn’t it?
Nah, just kidding, haha.
Honestly, I don’t think this book will make you better at math, however it may help you understand some complex theoretical concepts, since it doesn’t focus in the applied mathematics, but rather in the pure theory behind them.
The narration is fantastic and creative, and in fact, pretty attractive. Besides, the pictures and dares really complement the story. So whether you struggle with math or not, I would recommend to read this book. :)
P.S. I believe that the fact that the math geniuses are portrayed as devils is a pretty straight forward message... I mean, there’s math hell!! I know maths are mischievous and devilish, but this is literally saying *maths are hell*, isn’t it?
Nah, just kidding, haha.
October 30, 2018
I've been meaning to read this book for a long time, as it came highly recommended by both my kids. After reading it, I can see why. The author has written a loose structure of a novel in order to painlessly and seamlessly teach children some basic math concepts. Along the way, he makes math fun and interesting and accessible. (I actually happen to think math *is* fun and interesting and accessible, but I realize that not everyone does.)
The book is geared towards middle schoolers, but it works well for older children and adults as well. It also works well for both people who love math and its intricacies as well as people who are math-phobic, as it provides explanations and projects for experiential learners, all in a fun and light-hearted way.
I would best characterize the book as a novel about math. If that intrigues you, then read the book!
The book is geared towards middle schoolers, but it works well for older children and adults as well. It also works well for both people who love math and its intricacies as well as people who are math-phobic, as it provides explanations and projects for experiential learners, all in a fun and light-hearted way.
I would best characterize the book as a novel about math. If that intrigues you, then read the book!
March 19, 2020
Erano secoli che io e Benedetta dovevamo leggere insieme questo libro, e da qualche tempo lei continuava a dire che dovevamo proprio deciderci. Finalmente abbiamo trovato la voglia e il coraggio di affrontarlo, e devo dire che, soprattutto nella prima parte, ne e' proprio valsa la pena!
Ci siamo divertiti a guardare la matematica da una prospettiva un po' differente, molto giocosa, anche a ridere per il fatto che le sue reazioni erano spesso esattamente uguali a quelle di Roberto, il ragazzino protagonista della storia! Alle prese con la matematica i bambini reali e quelli immaginari si comportano allo stesso modo!
La cornice non e' sempre all'altezza forse, soprattutto nella seconda parte, ma tutto sommato si va avanti, e chissa' che adesso la matematica sara' guardata con occhio piu' benevolo dalla mia principessa.
Ci siamo divertiti a guardare la matematica da una prospettiva un po' differente, molto giocosa, anche a ridere per il fatto che le sue reazioni erano spesso esattamente uguali a quelle di Roberto, il ragazzino protagonista della storia! Alle prese con la matematica i bambini reali e quelli immaginari si comportano allo stesso modo!
La cornice non e' sempre all'altezza forse, soprattutto nella seconda parte, ma tutto sommato si va avanti, e chissa' che adesso la matematica sara' guardata con occhio piu' benevolo dalla mia principessa.
July 25, 2018
Nein, Nyet, Non, Nee, Votch, Nej, Nan, Oxi, Minime - how many ways can I say No to this book? As a certified math-phobic, I have to check in once in a while to see just what it is that causes my throat to close, my mind to go blank, and my skin to break out in a rash when faced with anything math related. I thought, "OK, how bad can a kid's book be?" The answer: Pretty fecking awful. Rutabaga numbers? What the hell are they talking about? Bonacci numbers? I thought the man's name was Fibonacci. Excuse me, I need to go take my allergy pills now and go lie down with a soothing book on something I can understand.
January 23, 2021
I am at my mothers house right now, which for me means rereading childhood classics that did not follow me to uni. This one isn't something I remember reading a lot, but somehow it made it on my nightstand.
It's cute, a math book for a young audience, and the beginning works well for me. However, it does become a bit tedious, especially since things are shown, not really explained and weird words are invented to do so. I now know why this didn't become a favorite of mine: you never quite learn why things are as they are or why you should care about them in the first place. So either you just like math or you don't - this will not change any attitudes.
Still, it has it's moments, and the illustrations are pretty nice.
It's cute, a math book for a young audience, and the beginning works well for me. However, it does become a bit tedious, especially since things are shown, not really explained and weird words are invented to do so. I now know why this didn't become a favorite of mine: you never quite learn why things are as they are or why you should care about them in the first place. So either you just like math or you don't - this will not change any attitudes.
Still, it has it's moments, and the illustrations are pretty nice.
July 15, 2017
Membuktikan bahwa tidak ada bukti adalah bukti itu sendiri.--p. 240
Buku ini nggak santai, lumayan buat pemanasan.
Saya menyarankan untuk yang menyukai matematika untuk membacanya. Ini, lho, ada novel yang beneran bahas perkara angka2 dengan balutan cerita.
Di buku ini, ceritanya yang jadi pemanis, matematika yang utama.
Review lengkap menyusul~~~
Buku ini nggak santai, lumayan buat pemanasan.
Saya menyarankan untuk yang menyukai matematika untuk membacanya. Ini, lho, ada novel yang beneran bahas perkara angka2 dengan balutan cerita.
Di buku ini, ceritanya yang jadi pemanis, matematika yang utama.
Review lengkap menyusul~~~
September 9, 2017
Ha sido como volver a estudiar las matemáticas de primaria pero con un toque mucho más divertido. Creo que es muy buen regalo para niños en primaria para demostrarles lo curiosas que pueden resultar las matemáticas.
February 18, 2020
Funny book about a number devil who meets a boy and converts him from a maths hater to a mathematician. My only bad thing is that it is maths but the story is funny.
January 17, 2026
Ik snap niet waarom mijn zonen dit boek niet wilden lezen. Het is fantasievol, je leert op een luchtige, grappige manier iets over wiskunde en het leest vlot. Ach, het zal die tweede reden wel zijn. Maar als ik dan iets navertelde uit het boek, vonden ze het wel weer interessant. Ach, papa.
April 3, 2019
Herkesin hoşlanacağını zannetmediğim ama benim çok sevdiğim kitap. Okullarda okuma listelerinde olmalı kesinlikle.
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