William Rutherford (mathematician)

William Rutherford (1798–1871) was an English mathematician famous for his calculation of 208 digits of the mathematical constant π in 1841.

Only the first 152 calculated digits were later found to be correct; but that broke the record of the time, which was held by the Slovenian mathematician Jurij Vega since 1789 (126 first digits correct). Rutherford used the following formula:

${\displaystyle {\pi \over 4}=4\arctan \left({1 \over 5}\right)-\arctan \left({1 \over 70}\right)+\arctan \left({1 \over 99}\right)}$