Robin Askew

Ever since *Longitude* and *Fermat’s Last Theorem* leapt off the shelves in quantities so-called bestselling novelists can only dream about, publishers have been falling over themselves in the scramble to find the next slim tome that humanises some arcane corner of scientific research while flattering its readership into believing that they’ve acquired a grasp on the concepts involved.

There have been a fair number of books on the mathematical mystery of pi over the years and David Blatner seems to have read them all. To be fair, he credits all his sources in this slight, flashily designed tome, whose gimmick is the inclusion of the first million digits of pi, reproduced in a vanishingly small point size and running across virtually every page. It’s an entertaining yarn taking us from the earliest mathematicians, whose ingenious but ultimately pointless method of calculating the ratio of a circle’s circumference to its diameter entailed the detailed production of polygons with billions of sides, all the way to the latest supercomputers which have now calculated pi to 51 billion digits. In between, we meet all manner of obsessives who devoted their entire lives to working out the first hundred or so digits (often, amusingly, getting it hopelessly wrong).

The breakthough, when it came, was not a matter of understanding but of sheer number-crunching power: in the late forties a certain D.F. Ferguson spent a year calculating the first 700 digits; tens years later, an early IBM computer achieved the same feat in 40 seconds. Now that computers have taken over the challenge of calculation, humans have turned to memorisation. The current record is held by one Hiroyuki Goto, who recited 42,000 digits from memory in February 1995.

For all this, there’s little practical application in knowing more than the first ten digits of pi, the exception being in testing of Pentium processors (if one digit is wrong then all subsequent digits will be wrong too, allowing easy detection of errors which may occur only once in a billion calculations). But David Blatner’s all-too-brief yet anecdote-rich romp through history and across cultures gives a hint of the enduring fascination inspired by the number that is, in the strict mathematical sense, both irrational and transcendental (i.e. it cannot be expressed algebraically nor as a ratio of integers), and may yet have secrets to yield. And if you thought the pi freaks were bonkers, wait until you read about the circle-squarers, or Geometric Cyclometers, who continue to insist that generations of mathematicians and scientists have been engaged in a sinister, sub-masonic conspiracy to conceal the real value of pi.