Pi chart. As this log chart shows, computations of pi have grown by 9 orders of magnitude, from 2037 to 1.241 trillion digits, in 53 years.

Pi in the Sky

The precision of pi has passed the trillion-digit mark--a sixfold increase over the previous record. Yasumasa Kanada and colleagues at the University of Tokyo recently announced the completion of a calculation of 1.241 trillion digits of mathematicians' favorite constant, 3.14159…

Kanada is the world's unquestioned pi king these days--he and his team have set virtually all the records since the mid-1980s. Their last one, in 1999, reached 206 billion digits. The latest calculation took over 400 hours on a Hitachi supercomputer. The programs for doing all the high-precision arithmetic, Kanada reports, were 5 years in the making. To nail down their result, the group actually computed pi with two different formulas.

What insights do all these digits offer? Not many, says David Bailey, a mathematician at Lawrence Berkeley National Laboratory, who computed a then-record 29 million digits in 1986. Pi primarily provides a convenient benchmark for measuring machines' ability to juggle huge numerical data sets quickly and accurately.

Related sites
Kanada's Web site
Computing Pi
More Pi pages on the Web