and computers set to work on these formulas have, as of this writing,
calculated to ten trillion (1013) decimal places!
Enter human memory. Pi geeks have taken on the challenge of
memorizing T and vie to be record holder of their school, country,
continent, or world. In 1973, the world record for memorizing digits
of mt was set and broken several times: 930, then 1,111, then 1,210.
By 1978 it was 10,000. By 1980 it was 20,013. From 1987 to 2005 the
world record was held by two individuals, both from Japan: first at
40,000 digits and then at 42,195.--2C¢-.
Figure 19.1. Piis the ratio of circumference (C) to diameter (D): C/D = tT.In 2005, Lu Chao, who was at the time a twenty-four-year-old
student in China, recited from memory 67,890 digits of m. He had
attempted to memorize Tm to 100,000 decimal places and was planning
to recite at least 90,000 of them, but he made an error at the 67,891st
decimal place, so that was the limit of his world-record performance.
At the point he made the error, Lu Chao had been reciting the digits of
mt for just over twenty-four hours, apparently without a break! Sleep
deprivation and general fatigue would certainly dispose him to im-