The most enjoyable introduction to the puzzles of mathematics. Wolfgang Bergmann in 'TV-Hören und Sehen'. Robert is tired of dreaming. Because the most terrifying things happen to him in his dreams, he decides to stop dreaming altogether. But he has not counted on the Number Devil! Suddenly, he appears, swirling around with his mysterious stick and conjuring whole sequences of numbers from it. Over twelve nights, he tells Robert about bouncing numbers, how to grow radishes, and that there are also imaginary numbers. For those who feel inspired by so many math problems, a little brain teaser awaits at the end of each chapter. 'The Number Devil' has been awarded the 'Luchs' and was one of the '7 best books for young readers'.