**What is Pi? | Pi Day**
https://www.piday.org/learn-about-pi/

WebPi: A Perennial Puzzle. Pi has interested people around the world for over 4,000 years. Many mathematicians – from famous ones such as Fibonacci, Newton, Leibniz, and Gauss, to lesser well-known mathematical minds – have toiled over pi, calculated its digits, and applied it in numerous areas of mathematics.

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