Numbers: Their Tales, Types, and Treasures

Two veteran math educators team up to produce a lighthearted, informal look at "the thing behind the symbol"%E2%80%94the history and weirdness of numbers. Posamentier (Mathematical Curiosities) and Thaller begin with a look into the origins of counting and number properties before examining numbers across history. Their timeline begins approximately 5,000 years ago with the Babylonians (who were the first to use a place-value system), advances through the Egyptians with their base-10 system, and reaches the invention of zero in India around 1,500 years ago. In addition to the expected coverage of special numbers, which includes the Fibonacci series, primes, pi, and the Golden Ratio, Posamentier and Thaller offer routes down odder mathematical byways to explain "perfect" and "amicable" numbers as well as the peculiarities of magic squares. Something that sets the book apart from other popular math titles is its exploration of the psychology of numbers and the fact that the human brain seems to be hard-wired for using them, whether keeping score of a game or setting a poetic meter. Posamentier and Thaller's entertaining volume never sacrifices depth for accessibility, and proves that math is much more than abstract calculation. (Aug.)