Around 250 B.C., the Greek mathematician Archimedes calculated the ratio of a circle’s circumference to its diameter. A precise determination of pi, as we know this ratio today, had long been of interest to the ancient Greeks, who strove for precise mathematical proportions in their architecture, music, and other art forms.
In Archimedes’ day, close approximations of pi had been known for over 1,000 years. An Egyptian document dated to 1650 B.C., for example, gives a value of 4 (8/9)2, or 3.1605. Archimedes’ value, however, was not only more accurate, it was the first theoretical, rather than measured, calculation of pi.