Keith Devlin, of Stanford University and known to many as NPR’s The Math Guy, has written a witty, enlightening, engaging and utterly accessible book about Leonardo di Pisa, of the familia Bonacci, the man who wrote the mother of all math books. Today’s math aficionados know him as Fibonacci (family/Bonacci) a nickname given him nearly six hundred years after his death.

How Devlin managed to pack so much information into such a slim volume is still a mystery to this reader, but I’m mighty glad he did. Most folks, on either side of the arithmetic fence, know of the Fibonacci numbers, and I suspect many copies of Devlin’s book will be purchased on that fact alone. For those readers anxious to learn more about Leonardo’s series of numbers, patience is the key word because that eagerly anticipated story comes very close to the end of the book. I have a feeling that all the math-loving readers understand patience.

In the meantime, Devlin mesmerizes the reader with history, geography, politics and always numbers; for it is numbers, and our efforts to add, subtract, multiply and divide them, that lie at the heart of Leonardo di Pisa’s story. The mark Fibonacci left on the world was not only his fabulous series of “cute as a bunny” numbers, but, more importantly, his 1202 arithmetic compilation and publication of Liber abbaci (Book of calculations) a much needed text bringing the usage of Hindu-Arabic numbers to the world of European commerce, at that time still entrenched in the unwieldy calculations of Roman numerals. This was the beginning of math for the masses, including a beautifully illustrated page of counting on one’s fingers.

“What Leonardo did was every bit as revolutionary as the personal computer pioneers” of the 1980s. Leonardo did not invent something; his “role was to ‘package’ and ‘sell’ the new methods to the world.” Liber abbaci was filled with practical arithmetic problems common to all sorts of tradespeople; yes, dear readers, we are talking about the dreaded WORD PROBLEM, known in 1202 as “rhetorical algebra.” With kindness toward those readers who are not math whizzes, Devlin not only explains these word problems, but then presents them in their more recognizable state as symbolic algebra.

Now we come to the Fibonacci numbers. It’s a wonderful story. It’s a word problem involving the multiplication of rabbits and the problem of the “division of food and money.” Leonardo’s description of this addition process “first appeared, it seems, in the Chadhshastra (The art of prosody) written by the Sanskrit grammarian Pingala sometime between 450 and 200 BCE.” Devlin then takes the reader through the Fibonacci numbers as found in Nature, Euclid and finally the Golden Ratio, which I assume that only degree-carrying mathematicians will understand. I can’t tell you more, except to say that if you love math (and I now understand there are legions who actually adore mathematics), then you have to read The Man of Numbers. On the other hand, if you hate math, but love finding out enough oddball facts to get you through every cocktail party till the day you die, you have to read The Man of Numbers. I haven’t come this close to liking arithmetic since first hearing Tom Lehrer’s New Math.

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