Pi, the ratio of a circle’s circumference to its diameter, has many origin stories from across the globe dating back thousands of years to ~1900 BCE when the Babylonians attempted to approximate the area of a circle, which is a common use of the constant today. The famous constant’s symbol, the Greek letter “π”, only became used in the 1700s with the symbol being widely popularised by Leonhard Euler in 1737.
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