Arima Yoriyuki

He approximated the value of ${\displaystyle \pi }$ and its square, ${\displaystyle \pi ^{2}}$. In 1766, he found the following rational approximation of pi, correct to 29 digits:[1][2]
${\displaystyle \pi \approx {\frac {428224593349304}{136308121570117}}=3.14159265358979323846264338327(569...)}$
1. ^ "Collection of approximations for ${\displaystyle \pi }$". Retrieved April 4, 2008.