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. It appears in many formulae across …

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 can have this Pi Day by checking out…

Pi, in mathematics, is the ratio of the circumference of a circle to its diameter. Because pi is irrational (not equal to the ratio of any two whole numbers), its digits do not repeat, and an approximation such …

Pi (pronounced like "pie") is often written using the Greek symbol π

100,000 Digits of Pi 3.141592653589793238462643383279502884197169399375105820974944592307816406286 ...

The greek small letter π (pi) is a geometric constant approximately equal to 3.1416. The numeric value is equal to the length of any circle's circumference divided by its diameter.

Learn about the number pi, why it is important in math, and what it is used to calculate!

Pi, the ratio of a circle’s circumference to its diameter, appears everywhere in nature. It helps explain circular and spiral patterns in the physical and biological world.

The following is a list of significant formulae involving the mathematical constant π. Many of these formulae can be found in the article Pi, or the article Approximations of π.

Discover recipes, home ideas, style inspiration and other ideas to try.