Fermat's Enigma

by Simon Singh

π can never be written down exactly, because the decimal places go on forever without any pattern. A beautiful feature of this random pattern is that it can be computed using an equation that is supremely regular: By calculating the first few terms, you can obtain a very rough value for π, but by calculating more and more terms an increasingly accurate value is achieved. Although knowing π to 39 decimal places is sufficient to calculate the circumference of the universe accurate to the radius of a hydrogen atom, this has not prevented computer scientists from calculating π to as many decimal places as possible. The current record is held by Yasumasa Kanada of the University of Tokyo, who calculated π to six billion decimal places in 1996.