Self-described math-phobe Robert begins having surreal dreams in which he encounters a number devil, who teaches him, just for starters, the crucial importance of zero and how to make all numbers out of ones. More difficult concepts are deliberately repeated in several dreams; occasional additional problems are provided for greater challenges. Infinitely more fun than the usual word-problem assignment.
Robert's not too happy when a diminutive number devil visits him in a dream--"If you give me some homework in my dream, I'll scream bloody murder! That's child abuse!"--but his opinion changes over the course of a dozen nights, as the devil shows him how to make numbers hop, introduces "unreasonable," "prima-donna," and "Bonacci" numbers, draws number triangles with all sorts of marvelous qualities, discusses one, zero, and infinity, and at the end delivers a dinner invitation to Number Heaven (which is also Number Hell), where Robert meets such mathematical eminences as Lord Rustle (as in Bertrand) and Dr. Happy Little (Felix Klein, inventor of the Klein Bottle), then has dessert--pie, of course. Berner adds plenty of full-color cartoon vignettes and charts; the author supplies several additional exercises for readers, and ends with translations of his quirky terminology and a long index of the concepts he so cleverly introduces. A natural follow-up to Norton Juster's The Phantom Tollbooth (1961) and Jon Scieszka's Math Curse (1995), covering more mathematical territory--with less plot--than either, but sharing the same daffy sensibility.
Exceptionally handsome four-color illustrations and vignettes deepen the magic of this mathematically minded fantasy, Enzensberger's (Europe, Europe) first book for children. Robert is plagued by bad dreams until a mysterious creature called the Number Devil appears to him one night. Robert, who hates everything to do with numbers, thinks it just another nightmare, but, surprisingly, finds himself fascinated by the intricacies of mathematics as taught by the exacting but always enthusiastic Devil. In a series of 12 dreams, Robert (and the reader) are introduced to ever more complex theories, from different kinds of infinity to triangular numbers. In Number Hell/Number Heaven, Robert and the Devil meet famous mathematicians of the past and Robert is inducted into the ranks of number apprentices. Surreal touches (numbers flying in the air, floating in a swimming pool), fanciful names for mathematical terms (prima-donna numbers for prime numbers) and problems posed directly to the reader contribute to the playful tone. The generous and strategic use of color, however, provides the biggest boost: even mathematical equations look festive here, hand-printed in warm muted tones. Berner's witty spot and full-page illustrations also work to clarify mathematical principles. Many readers, unused to a novel of ideas, may well be daunted by the string of mathematical concepts, particularly because the reasoning behind several of the "tricks" demonstrated by the Devil is only glancingly addressed. But for certain kinds of readers--chess players, puzzle enthusiasts--this will be a favorite. Ages 11-up. (Oct.)
In a starred review, PW noted that "exceptionally handsome four-color illustrations and vignettes deepen the magic of this mathematically minded fantasy. For certain kinds of readers–chess players, puzzle enthusiasts–this will be a favorite." Ages 11-up. (May)
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Gr 6 Up-This book consists of a dozen unusual dreams of Robert, a 12 year old who thinks math is "a waste of time." The number devil who visits him each night changes that with magical demonstrations of mathematical concepts that intrigue the boy. Starting simply with the concept of infinity, the devil introduces prime numbers, square roots, Fibonacci numbers, and more, inventively using coconuts, multiplying rabbits, and other oddities as examples. He demonstrates concepts in imaginative ways that actually make sense, focusing on general principles, with an emphasis on the pleasing consistency of mathematics. Robert becomes interested and is named a "number apprentice" in the final chapter. Building new concepts from those previously learned makes the progression to more complicated areas easier and satisfying. The devil uses made-up terms (e.g., square roots are called "rutabagas") and the author warns that students should learn the correct words. A helpful index identifies these terms, and also reveals the identities of various mathematicians referred to by other names (Johan van de Lune is the "Man in the Moon"). Colorful, cartoon illustrations appear throughout, along with useful tables and diagrams. The dream world recalls Alice's Adventures in Wonderland and Norton Juster's The Phantom Tollbooth (Knopf, 1961), but the attempts at humor and silliness here never match the wit and charm of those classics. Although it is not a fully realized fantasy, The Number Devil may intrigue and teach readers willing to try an unusual introduction to math principles.-Steven Engelfried, West Linn Public Library, OR