Ludolphian number

English

Van Ceulen's De Circulo & Adscriptis Liber

Etymology

From Ludolph van Ceulen, a German mathematician who improved on previous approximations of pi.

Noun

Ludolphian number (uncountable)

1. (mathematics, chiefly historical) Synonym of pi, particularly the 35-decimal approximation discovered by Ludolph van Ceulen
   • 1992 March 2, Richard Preston, “The Mountains of Pi”, in The New Yorker:

     Pi... came to be called the Ludolphian number, after Ludolph van Ceulen, a German mathematician who approximated it to thirty-five decimal places... a calculation that took Ludolph most of his life to accomplish, and gave him such satisfaction that he had the digits engraved on his tombstone... the stone vanished, possibly to be turned into a sidewalk slab. Somewhere in Leiden, people may be walking over Ludolph's digits.