March 14 is Pi Day, an annual celebration of the mathematical constant of pi, representing the ratio of a circle's circumference to its diameter. The holiday is observed on March 14 or 3/14 because 3.14 are the first three digits of the infinite number pi — 3.14159 ... and on and on.

Celebrate Pi Day on March 14 with math enthusiasts worldwide, honoring the infinite and practical uses of the mathematical constant.

WEST PALM BEACH, Fla. (AP) — Math enthusiasts around the world, from college students to rocket scientists, celebrate Pi Day, which is March 14 or 3/14 — the first three digits of an infinite number with many practical uses. Many people will mark the day with a slice of pie — sweet, savory or even pizza.