William Jones first introduced the π symbol for the mathematical constant pi in 1706.

Historical Context

The Welsh mathematician William Jones used π in his book Synopsis Palmariorum Matheseos , representing the ratio of a circle's circumference to its diameter—chosen as the first letter of the Greek word "periphery" (περιφέρεια). This notation replaced lengthy descriptions like "quantitas circumferentiæ ad diametrum." Leonhard Euler later popularized it in the 1730s, making it standard worldwide.

Key Milestones

  • 1706 : William Jones pioneers π in print.
  • 1737 : Euler adopts and spreads its use.
  • Pi Day (March 14) : Celebrates 3.14, near today's date in 2026—perfect timing as it's observed globally since 1988.

Jones, a self-taught scholar and friend of Isaac Newton, bridged older traditions with modern notation, sparking a symbol still vital in math and engineering today.

TL;DR : The last name is Jones —credited with inventing the π symbol.

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