''The Number Devil: A Mathematical Adventure'' (german: Der Zahlenteufel. Ein Kopfkissenbuch für alle, die Angst vor der Mathematik haben) is a book for children and young adults that explores mathematics. It was originally written in 1997 in German by
Hans Magnus Enzensberger
Hans Magnus Enzensberger (11 November 1929 – 24 November 2022) was a German author, poet, translator, and editor. He also wrote under the pseudonyms Andreas Thalmayr, Elisabeth Ambras, Linda Quilt and Giorgio Pellizzi. Enzensberger was regarde ...
and illustrated by
Rotraut Susanne Berner
Rotraut Susanne Berner (born 26 August 1948, in Stuttgart) is a German graphic designer and illustrator. She illustrated '' The Number Devil'' by Hans Magnus Enzensberger.
She is well known for a series of popular children's book, called Wimme ...
. The book follows a young boy named Robert, who is taught mathematics by a sly "number devil" called Teplotaxl over the course of twelve dreams.
The book was met with mostly positive reviews from critics, approving its description of math while praising its simplicity. Its colorful use of fictional mathematical terms and its creative descriptions of concepts have made it a suggested book for both children and adults troubled with math. ''The Number Devil'' was a
bestseller
A bestseller is a book or other media noted for its top selling status, with bestseller lists published by newspapers, magazines, and book store chains. Some lists are broken down into classifications and specialties (novel, nonfiction book, coo ...
in Europe, and has been translated into English by
Michael Henry Heim
Michael Henry Heim (January 21, 1943 – September 29, 2012) was a professor of Slavic languages at the University of California at Los Angeles. He was an active and prolific translator, and was fluent in Czech, Russian, Serbo-Croatian, Hung ...
.
Plot
Robert is a young boy who suffers from
mathematical anxiety
Mathematical anxiety, also known as math phobia, is anxiety about one's ability to do mathematics.
Math Anxiety
Mark H. Ashcraft defines math anxiety as "a feeling of tension, apprehension, or fear that interferes with math performance" (2002, p.& ...
due to his boredom in school. His mother is Mrs. Wilson. He also experiences
recurring dream
A recurring dream is a dream which is experienced repeatedly over a long period. They can be pleasant or nightmarish and unique to the person and their experiences.
Common themes in recurring dreams
Through psychological analyses and studies, so ...
s—including falling down an endless slide or being eaten by a giant fish—but is interrupted from this sleep habit one night by a small
devil
A devil is the personification of evil as it is conceived in various cultures and religious traditions. It is seen as the objectification of a hostile and destructive force. Jeffrey Burton Russell states that the different conceptions of ...
creature who introduces himself as the Number Devil. Although there are many Number Devils (from Number Heaven), Robert only knows him as the Number Devil before learning of his actual name, Teplotaxl, later in the story.
Over the course of twelve dreams, the Number Devil teaches Robert mathematical principles. On the first night, the Number Devil appears to Robert in an oversized world and introduces the number
one
1 (one, unit, unity) is a number representing a single or the only entity. 1 is also a numerical digit and represents a single unit of counting or measurement. For example, a line segment of ''unit length'' is a line segment of length 1. ...
. The next night, the Number Devil emerges in a forest of trees shaped like "ones" and explains the necessity of the number
zero
0 (zero) is a number representing an empty quantity. In place-value notation such as the Hindu–Arabic numeral system, 0 also serves as a placeholder numerical digit, which works by multiplying digits to the left of 0 by the radix, usu ...
,
negative number
In mathematics, a negative number represents an opposite. In the real number system, a negative number is a number that is inequality (mathematics), less than 0 (number), zero. Negative numbers are often used to represent the magnitude of a loss ...
s, and introduces ''hopping'', a fictional term to describe
exponentiation
Exponentiation is a mathematical operation, written as , involving two numbers, the '' base'' and the ''exponent'' or ''power'' , and pronounced as " (raised) to the (power of) ". When is a positive integer, exponentiation corresponds to re ...
. On the third night, the Number Devil brings Robert to a cave and reveals how ''prima-donna'' numbers (
prime number
A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only way ...
s) can only be
divided
Division is one of the four basic operations of arithmetic, the ways that numbers are combined to make new numbers. The other operations are addition, subtraction, and multiplication.
At an elementary level the division of two natural numbers ...
by themselves and one without a
remainder
In mathematics, the remainder is the amount "left over" after performing some computation. In arithmetic, the remainder is the integer "left over" after dividing one integer by another to produce an integer quotient (integer division). In algeb ...
. Later, on the fourth night, the Number Devil teaches Robert about ''
rutabaga
Rutabaga (; North American English) or swede (British English and some Commonwealth English) is a root vegetable, a form of ''Brassica napus'' (which also includes rapeseed). Other names include Swedish turnip, neep (Scots), and Turnip (termin ...
s'', another fictional term to depict
square root
In mathematics, a square root of a number is a number such that ; in other words, a number whose ''square'' (the result of multiplying the number by itself, or ⋅ ) is . For example, 4 and −4 are square roots of 16, because .
...
s, at a beach.
For a time after the fourth night, Robert cannot find the Number Devil in his dreams; later, however, on the fifth night, Robert finds himself at a desert where the Number Devil teaches him about
triangular numbers
A triangular number or triangle number counts objects arranged in an equilateral triangle. Triangular numbers are a type of figurate number, other examples being square numbers and cube numbers. The th triangular number is the number of dots in ...
through the use of coconuts. On the sixth night, the Number Devil teaches Robert about the natural occurrence of
Fibonacci numbers
In mathematics, the Fibonacci numbers, commonly denoted , form a sequence, the Fibonacci sequence, in which each number is the sum of the two preceding ones. The sequence commonly starts from 0 and 1, although some authors start the sequence from ...
, which the Number Devil shortens to ''Bonacci numbers'', by counting brown and white rabbits as they
reproduce
Reproduction (or procreation or breeding) is the biological process by which new individual organisms – "offspring" – are produced from their "parent" or parents. Reproduction is a fundamental feature of all known life; each individual org ...
multiple times. By this dream, Robert's mother has noticed a visible change in Robert's mathematical interest, and Robert begins going to sleep earlier to encounter the Number Devil. The seventh night brings Robert to a bare, white room, where the Number Devil presents
Pascal's triangle
In mathematics, Pascal's triangle is a triangular array of the binomial coefficients that arises in probability theory, combinatorics, and algebra. In much of the Western world, it is named after the French mathematician Blaise Pascal, althoug ...
and the patterns that the
triangular array
In mathematics and computing, a triangular array of numbers, polynomials, or the like, is a doubly indexed sequence in which each row is only as long as the row's own index. That is, the ''i''th row contains only ''i'' elements.
Examples
Notable ...
displays. On the eighth night, Robert is brought to his classroom at school. The Number Devil arranges Robert's classmates in multiple ways, teaches him about
permutation
In mathematics, a permutation of a set is, loosely speaking, an arrangement of its members into a sequence or linear order, or if the set is already ordered, a rearrangement of its elements. The word "permutation" also refers to the act or p ...
s, and what the Number Devil calls ''vroom numbers'' (
factorial
In mathematics, the factorial of a non-negative denoted is the product of all positive integers less than or equal The factorial also equals the product of n with the next smaller factorial:
\begin
n! &= n \times (n-1) \times (n-2) ...
s).
On the ninth night, Robert dreams he is in bed, suffering from the flu, when the Number Devil appears next to him. The Number Devil teaches Robert about
natural numbers
In mathematics, the natural numbers are those numbers used for counting (as in "there are ''six'' coins on the table") and ordering (as in "this is the ''third'' largest city in the country").
Numbers used for counting are called '' cardinal ...
, which the Number Devil calls ''garden-variety numbers'', the unusual characteristics of
infinite
Infinite may refer to:
Mathematics
*Infinite set, a set that is not a finite set
*Infinity, an abstract concept describing something without any limit
Music
*Infinite (group)
Infinite ( ko, 인피니트; stylized as INFINITE) is a South Ko ...
, and
infinite series
In mathematics, a series is, roughly speaking, a description of the operation of adding infinitely many quantities, one after the other, to a given starting quantity. The study of series is a major part of calculus and its generalization, ma ...
. Robert finds himself at the
North Pole
The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is the point in the Northern Hemisphere where the Earth's rotation, Earth's axis of rotation meets its surface. It is called the True North Pole to distingu ...
, where the Number Devil introduces
irrational number
In mathematics, the irrational numbers (from in- prefix assimilated to ir- (negative prefix, privative) + rational) are all the real numbers that are not rational numbers. That is, irrational numbers cannot be expressed as the ratio of two inte ...
s (''unreasonable numbers''), as well as aspects of
Euclidean geometry
Euclidean geometry is a mathematical system attributed to ancient Greek mathematician Euclid, which he described in his textbook on geometry: the ''Elements''. Euclid's approach consists in assuming a small set of intuitively appealing axioms ...
edges
Edge or EDGE may refer to:
Technology Computing
* Edge computing, a network load-balancing system
* Edge device, an entry point to a computer network
* Adobe Edge, a graphical development application
* Microsoft Edge, a web browser developed by ...
(''lines''). By the eleventh night, Robert has shown considerable increased interest in mathematics, but questions its validity, to which the Number Devil introduces the concept of
mathematical proof
A mathematical proof is an Inference, inferential Argument-deduction-proof distinctions, argument for a Proposition, mathematical statement, showing that the stated assumptions logically guarantee the conclusion. The argument may use other previo ...
s, ending with the Number Devil showing Robert a complicated proof of basic
arithmetic
Arithmetic () is an elementary part of mathematics that consists of the study of the properties of the traditional operations on numbers—addition, subtraction, multiplication, division, exponentiation, and extraction of roots. In the 19th c ...
. On the twelfth night, Robert and the Number Devil receive an invitation (which names the Number Devil as Teplotaxl) to Number Heaven, as Robert's time with the Number Devil has finished. At Number Heaven, Robert learns of
imaginary number
An imaginary number is a real number multiplied by the imaginary unit , is usually used in engineering contexts where has other meanings (such as electrical current) which is defined by its property . The square of an imaginary number is . Fo ...
s, which Teplotaxl describes as ''imaginative numbers'', as well as the
Klein bottle
In topology, a branch of mathematics, the Klein bottle () is an example of a non-orientable surface; it is a two-dimensional manifold against which a system for determining a normal vector cannot be consistently defined. Informally, it is a ...
. Walking through Number Heaven, Teplotaxl introduces Robert to various famous
mathematician
A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems.
Mathematicians are concerned with numbers, data, quantity, mathematical structure, structure, space, Mathematica ...
s, such as
Fibonacci
Fibonacci (; also , ; – ), also known as Leonardo Bonacci, Leonardo of Pisa, or Leonardo Bigollo Pisano ('Leonardo the Traveller from Pisa'), was an Italian mathematician from the Republic of Pisa, considered to be "the most talented Western ...
, whom Teplotaxl calls ''Bonacci'', and
George Cantor
Georg Ferdinand Ludwig Philipp Cantor ( , ; – January 6, 1918) was a German mathematician. He played a pivotal role in the creation of set theory, which has become a fundamental theory in mathematics. Cantor established the importance of ...
, or ''Professor Singer''. The book ends with Robert in class using his newfound mathematical knowledge.
History
Enzensberger fostered a passion for mathematics and numbers, although he was not a mathematician by trade. In 1998, he delivered a speech at the
International Congress of Mathematicians
The International Congress of Mathematicians (ICM) is the largest conference for the topic of mathematics. It meets once every four years, hosted by the International Mathematical Union (IMU).
The Fields Medals, the Nevanlinna Prize (to be rename ...
criticizing the isolation of mathematics from popular culture. ''The Number Devil'' was ultimately written on suggestion from Enzensberger's eleven-year-old daughter Theresia. Because he was displeased with the way mathematics was taught to students at school, the German author decided to pen a book that teaches mathematics in an innovative way. German illustrator
Rotraut Susanne Berner
Rotraut Susanne Berner (born 26 August 1948, in Stuttgart) is a German graphic designer and illustrator. She illustrated '' The Number Devil'' by Hans Magnus Enzensberger.
She is well known for a series of popular children's book, called Wimme ...
provided many full-page illustrations, as well as smaller drawings, for the book. ''The Number Devil'' was first published in German in 1997. ''The Number Devil'' has been noted for its unorthodox abandonment of standard
notation
In linguistics and semiotics, a notation is a system of graphics or symbols, characters and abbreviated expressions, used (for example) in artistic and scientific disciplines to represent technical facts and quantities by convention. Therefore, ...
; instead, Enzensberger created a variety of fictional terms to help describe mathematical concepts. For instance,
exponentiation
Exponentiation is a mathematical operation, written as , involving two numbers, the '' base'' and the ''exponent'' or ''power'' , and pronounced as " (raised) to the (power of) ". When is a positive integer, exponentiation corresponds to re ...
takes the term ''hopping'', and the fictional term ''unreasonable numbers'' was coined for
irrational number
In mathematics, the irrational numbers (from in- prefix assimilated to ir- (negative prefix, privative) + rational) are all the real numbers that are not rational numbers. That is, irrational numbers cannot be expressed as the ratio of two inte ...
s. The
UCLA
The University of California, Los Angeles (UCLA) is a public university, public Land-grant university, land-grant research university in Los Angeles, California. UCLA's academic roots were established in 1881 as a Normal school, teachers colle ...
Professor of Slavic Languages
Michael Henry Heim
Michael Henry Heim (January 21, 1943 – September 29, 2012) was a professor of Slavic languages at the University of California at Los Angeles. He was an active and prolific translator, and was fluent in Czech, Russian, Serbo-Croatian, Hung ...
translated the book from German to English. The translation was particularly difficult in that it required special attention to the numerical aspect of the book. He was also challenged by the necessity to use simple English words appropriate for the target audience of ''The Number Devil''—that is, children aged eleven to fourteen. The mathematics book was then published in English in 1998.
The book was a hit across Europe, becoming a best seller in at least Spain, Germany, the Netherlands, and Italy. ''The Number Devil'' also had considerable success in Japan. After the success of ''The Number Devil'', Enzensberger wrote a follow-up, called ''Where Were You, Robert?'', a children's book focusing on history rather than math. The German author has since stated he will not write any more young adult's books, but instead direct his effort towards
poetry
Poetry (derived from the Greek '' poiesis'', "making"), also called verse, is a form of literature that uses aesthetic and often rhythmic qualities of language − such as phonaesthetics, sound symbolism, and metre − to evoke meanings ...
.
Viva Media
Encore Software, LLC ("Encore") is a Delaware limited liability company focused on software sales, distribution and software development.
In November 2008, Encore announced an expanded license with Riverdeep. Under the terms of the agreement Enco ...
later published an
educational
Education is a purposeful activity directed at achieving certain aims, such as transmitting knowledge or fostering skills and character traits. These aims may include the development of understanding, rationality, kindness, and honesty. Vari ...
computer game
Video games, also known as computer games, are electronic games that involves interaction with a user interface or input device such as a joystick, controller, keyboard, or motion sensing device to generate visual feedback. This feedbac ...
, similarly titled ''The Number Devil: A Mathematical Adventure'', based on the book. An
audiobook
An audiobook (or a talking book) is a recording of a book or other work being read out loud. A reading of the complete text is described as "unabridged", while readings of shorter versions are abridgements.
Spoken audio has been available in sch ...
was also released for ''The Number Devil''.
Reception
''The Number Devil'' received mostly positive reviews from critics. Mathematics professor
John Allen Paulos
John Allen Paulos (born July 4, 1945) is an American professor of mathematics at Temple University in Philadelphia, Pennsylvania. He has gained fame as a writer and speaker on mathematics and the importance of mathematical literacy. Paulos write ...
of
Temple University
Temple University (Temple or TU) is a public university, public Commonwealth System of Higher Education, state-related research university in Philadelphia, Pennsylvania. It was founded in 1884 by the Baptists, Baptist minister Russell Conwell an ...
wrote an article for ''
The New York Review of Books
''The New York Review of Books'' (or ''NYREV'' or ''NYRB'') is a semi-monthly magazine with articles on literature, culture, economics, science and current affairs. Published in New York City, it is inspired by the idea that the discussion of i ...
'', praising ''The Number Devil'' as a "charming numerical fairy tale for children." Likewise, mathematics writer
Martin Gardner
Martin Gardner (October 21, 1914May 22, 2010) was an American popular mathematics and popular science writer with interests also encompassing scientific skepticism, micromagic, philosophy, religion, and literatureespecially the writings of L ...
of the ''
Los Angeles Times
The ''Los Angeles Times'' (abbreviated as ''LA Times'') is a daily newspaper that started publishing in Los Angeles in 1881. Based in the LA-adjacent suburb of El Segundo since 2018, it is the sixth-largest newspaper by circulation in the ...
'' applauded Enzensberger's introduction of mathematics "in such an entertaining way." In a book review for ''
The Baltimore Sun
''The Baltimore Sun'' is the largest general-circulation daily newspaper based in the U.S. state of Maryland and provides coverage of local and regional news, events, issues, people, and industries.
Founded in 1837, it is currently owned by Tr ...
'', Michael Pakenham approved of the book's simplicity, writing, "it's not incomprehensible. Not for a minute."
Not all reviews were positive, however. The
American Mathematical Society
The American Mathematical Society (AMS) is an association of professional mathematicians dedicated to the interests of mathematical research and scholarship, and serves the national and international community through its publications, meetings ...
's
Deborah Loewenberg Ball
Deborah Loewenberg Ball is an educational researcher noted for her work in mathematics instruction and the mathematical preparation of teachers. From 2017 to 2018 she serves as president of the American Educational Research Association. She serve ...
fantasy
Fantasy is a genre of speculative fiction involving magical elements, typically set in a fictional universe and sometimes inspired by mythology and folklore. Its roots are in oral traditions, which then became fantasy literature and drama ...
," the two mathematicians found several issues. Ball and Bass were concerned with ''The Number Devil'' negative characterization of
math teacher
In contemporary education, mathematics education, known in Europe as the didactics or pedagogy of mathematics – is the practice of teaching, learning and carrying out scholarly research into the transfer of mathematical knowledge.
Although re ...
s, its apparent presentation of mathematics as
magical
Magical is the adjective for magic. It may also refer to:
* Magical (horse) (foaled 2015), Irish Thoroughbred racehorse
* "Magical" (song), released in 1985 by John Parr
* '' Magical: Disney's New Nighttime Spectacular of Magical Celebrations'', ...
rather than
factual
A fact is a datum about one or more aspects of a circumstance, which, if accepted as true and proven true, allows a logical conclusion to be reached on a true–false evaluation. Standard reference works are often used to check facts. Scient ...
, and a number of other contentions.
Ted Dewan
TED may refer to:
Economics and finance
* TED spread between U.S. Treasuries and Eurodollar
Education
* ''Türk Eğitim Derneği'', the Turkish Education Association
** TED Ankara College Foundation Schools, Turkey
** Transvaal Education Depart ...
, writing for the ''
Times Educational Supplement
''Tes'', formerly known as the ''Times Educational Supplement'', is a weekly UK publication aimed at education professionals. It was first published in 1910 as a pull-out supplement in ''The Times'' newspaper. Such was its popularity that in 19 ...
'', believed it to be "far more compelling than a standard text," but found it less adventurous than he hoped for. He also criticized its use in mathematics education, stating "I suspect this is the sort of book that well-meaning adults will mistakenly thrust upon children because it will be good for them."