Been pestering your child through the summer to finish the latest Harry Potter so you can read it? Anxiously awaiting The Amber Spyglass, the final instalment of Philip Pullman's Dark Materials trilogy? In spite of certain national newspapers' steadfast refusal to include mega-selling children's books in general best-seller listings, a great many adults are unapologetic about reading something ostensibly for children.
From the children's non-fiction list came Sophie's World, which probably introduced modern philosophy to more adults than kids. When it comes to mathematics, the two great so-called "children's" fantasies that usually spring to mind are Alice in Wonderland and Flatland by Edwin A Abbott. Alice's deep mathematical underpinning is fortified by a matrix of riddles and contemporary university politics; the genius of Flatland is itself mathematical, employing a conceptual "transform" to make fourth-dimensional mathematics tangible to us 3-D people. Both these books, of course, have enjoyed an extensive adult readership.
Hans Magnus Enzensberger's "mathematical adventure" has been compared with Alice and Flatland, at least by its publisher, which hopes it will attract adult maths-phobics as well as children. The Number Devil chronicles a reluctant boy's nightly betwitchment by a mischievous mentortormentor who introduces him to a world of intriguing number play. Among the more colourful subjects covered are triangular numbers, irrational numbers, series, topological objects, Fibonacci numbers, periodic decimal fractions, and an insight into what mathematicians' work consists of.
Keen to redefine the meaning of mathematics, especially to those disenchanted by ridiculous word problems, Enzensberger promises readers that they won't have to do a single problem. Instead, Rotraut Suzanne Berner's illustrations reveal the beauty of numbers via visual patterns and diagrams. There's a hint of subversion throughout the book; the boy's maths teacher is made out to be a dunderhead, and calculators (some as big as sofas) are skilfully employed as tools for exposing the beauties of mathematics.
Enzensberger coins colourful terms for mathematical operations (for instance, "rutabaga" for square root and "vroom" for factorial). I enjoyed most of these substitutions until they extended to the names of historical figures (Bertrand Russell is no friendlier when disuised as "Rustle", and why shorten the marvellously fun Fibonacci to "Bonacci"?) I bought The Number Devil when it came out in the US in 1998 on the strength of its irresistible title and excellent Continental design. I was also intrigued by the whimsical intellectual atmosphere created by Berner's sophisticated illustrations. The story itself was enlivened by little magical touches, such as the Number Devil's sky-writing cane. However, in the end, the story's charm seemed mainly superficial; although the Number Devil is red, has access to some extraordinary audio-visual equipment, and occasionally explodes, his performance is what you might expect from a creative and well-informed maths teacher with only one student and no curriculum. Neither did the Devil win my affection as much as Robert's sorrow at his departure assumed it had; he is meant to be endearingly annoying, but in 250-plus pages he didn't enlist my sympathy or raise my ire to any great extent. Robert, the perpetually pyjama'd boy pupil, is a bland character; not much more than a line-feeder enabling the Number Devil to get on with the agenda.
While The Number Devil makes mathematics far more compelling than a standard text, and the episodes are well-sequenced mathematically, they add up to a series of lessons with colourful dialogue rather than something I'd describe as an "adventure". The tale uses the narrative device of a series of dreams for no apparent reason (other than to apologise for the Number Devil's surreal world); hardly state-of-the-art when compared with the writing of Philip Pullman, for example.
I suspect this is the sort of book that well-meaning adults will mistakenly thrust upon children because it will be Good for Them, not necessarily a book that one child would heartily recommend to another.
It's difficult for any writer to seduce the mathematically disenchanted into an appreciation of the subtle beauties and patterns of maths. Perhaps The Number Devil is best described as a pretend children's book for adults who want to familiarise themselves with what's going on in the ivory towers. Those who are curious as to what lies beyond the algebra and trig they learned at school, or anyone teaching maths, will undoubtedly find some of the ideas and approaches in The Number Devil well worth taking in.
Although I cannot see this tale being narrative non-fiction's answer to the Harry Potter books, with their mass adult and child appeal, it's certainly a merry jaunt through the corridors of mathematical theory.