Gardner's latest collection of mathematical diversions is witty, literate, and properly maddening. The puzzles range from the traditional stuff with coins and cards to more esoteric maneuverings of infinities (yes, there's more than one). The anti-mathematical will probably be most interested in Gardner's accounts of Freud's flirtation with numerology and Escher's fascination with topological and geometric conundrums. For those whose goal is self-improvement, Gardner leaks many of the secrets of the ""lightning calculators,"" who multiply seven-digit numbers in their heads. Pascal's Triangle, ever an attraction for the mathematical inquirer, also gets its due as a source of puzzle and enlightenment. Yes, there are answers, and Gardner (who's been Puzzles Editor at The Scientific American for years) has included addenda to the original published columns that incorporate sallies and comments from calculating readers.