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

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.

100,000 Digits of Pi 3.141592653589793238462643383279502884197169399375105820974944592307816406286 ...

Learn about the definition of pi in relation to a circle with this BBC Bitesize Maths article. For students between the ages of 11 and 14.

Pi, or π, is a number that is used to represent the ratio between a circle's circumference and its diameter. The value of pi is always the same no matter how big the circle is. Its actual value ...

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