The number π (/ paɪ / ⓘ; spelled out as pi) is a mathematical constant, approximately equal to 3.14159, that is the ratio of a circle 's circumference to its diameter.

The first million digits of pi (π) are below. Why not calculate the circumference of a circle using pi here. Or simply learn about pi here. Maximize the fun you…

Mar 2, 2026 · pi (π), in mathematics, the ratio of the circumference of a circle to its diameter. The Greek letter π was first used by British mathematician William Jones in 1706 to represent the ratio …

9 hours ago · As people celebrate Pi Day this March 14, the mathematical constant continues to be part of everyday life for scientists and engineers.

Then the circumference (all the way around the circle) is 3.14159265... a number known as Pi. Pi (pronounced like "pie") is often written using the Greek symbol π. With a diameter of D the …

20 hours ago · Every year, math nerds and dessert enthusiasts unite to celebrate Pi Day on March 14, a date whose digits represent the first three digits of the mathematical constant pi.

1 day ago · Celebrate Pi Day and read about how this number pops up across math and science on our special Pi Day page. For more than two millennia, mathematicians have produced a growing heap of …

Pi is a constant value. That is, the ratio of the circumference to the diameter is the same for all circles. The drawing below shows the circumference of a circle that has been "straightened out." It is a little …

5 days ago · What Is Pi? (Grades 5-8) This article is for students grades 5-8. What is Pi? Pi is a number. You might know it as 3.14 or the symbol π. But it’s way more than that! What Makes Pi Special? Pi is …

The 1998 film Pi is a dark, strange, and hyperkinetic movie about a mathematician who is slowly going insane searching for a pattern to the Stock Market. Both a Hasidic cabalistic sect and a Wall Street …