The Number Devil

The Number Devil is a book for children and upwards which explores mathematics by Hans Magnus Enzensberger. It was originally written in German and illustrated by Rotraut Susanne Berner.

In the book, a young boy named "Robert" encounters a sly number devil called Teplotaxl through the course of twelve dreams.

This book was a bestseller, and has been translated into 22 languages.

Fictional terms

The book uses fictional terms to describe aspects of maths that would otherwise sound very unappealing to children. Some examples are:

* "vroom", factorial
* "prima-donnas", prime numbers
* "rutabagas", square roots
* "unreasonable number", irrational number
* "coconuts", triangular numbers (referring to the instance in the book when they drop coconuts onto the ground, forming triangles)
* "hopping", exponent
* "number triangle", numbers on Pascal's Triangle

The book also refers to real-life mathematicians by imaginary names. Examples include:

* "Professor Horrors", Carl Friederich Gauss
* "Lord Rustle", Bertrand Russell
* "Owl", Leonhard Euler
* "Dr Happy Little", Felix Klein
* "Man in the Moon", Johan van de Lune
* "Bonacci", Fibonacci
* "Professor Singer", Georg Cantor

A computer game was made based on the book.