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Books > Pi, the world’s most mysterious number September 24, 2006

Posted by grhomeboy in Books Life.

Pi: A Biography of the World’s Most Mysterious Number
By Alfred S. Posamentier and Ingmar Lehmann
Prometheus Books
ISBN 1-59102-200-2
AUD$52.95 324 pages
Good old pi. The ratio of the circumference of a circle to its diameter. According to this book, pi’s been known, in an approximate form, since about 2000bc. And, of course, because the thing is ‘irrational’ (a number which can’t be expressed as a finite decimal number) we will never have anything but approximations. It’s just that nowadays that approximation goes to 1.24 trillion decimal places!

This book has chapters on the history of pi (an exhaustive chronicle of the increasing accuracy of the approximation of pi across many cultures, including Ancient Egyptians, the Babylonians, Ancient Greeks, Chinese and Romans, right up to the present) as well as chapters about the paradoxes, curiosities and the applications of pi. It has proofs and ways of calculating the value of pi. It also touches on some of the greatest mathematical minds because they were fascinated by pi. And to top it all off, Posamentier and Lehmann provide us with a lovely 27 pages filled with nothing more than pi to one hundred thousand decimal places.

This is a book for enthusiasts, trivial pursuit addicts or wannabe nerds. It has too many equations and too much mathematical notation to attract a general lay readership and it’s too basic and flippant to interest professional mathematicians. As well, it doesn’t come anywhere close to approaching the beauty or scope of books such as Mario Livio’s The Golden Ratio, John McLeish’s Number, or John Barrow’s The Book of Nothing.

I suppose you can learn something from almost anything. From this book, I learned that International Pi Day is March 14, not because this is Einstein’s birthday, which it is, but because this date can be written as 3.14, which is pi to two decimal places.

If you like that kind of stuff, you’ll find something to enjoy in this book.

Pi chart
Pi first became known as such in 1706 when mathematician William Jones used it in his own method of relating the circumference of a circle to its diameter. Why did he opt for Π rather than some other symbol? Phonetics: pi sounds like ‘p’ (for ‘perimeter’). The rough numerical value of pi was known as long ago at 1650bc, as demonstrated on a surviving papyrus scroll.

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