WEST PALM BEACH, March 15 -- 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.

Simply put, pi is a mathematical constant that expresses the ratio of a circle's circumference to its diameter. It figures into numerous formulas used in physics, astronomy, engineering and other fields, dating back thousands of years to ancient Egypt, Babylon and China.

Pi Day itself dates to 1988, when physicist Larry Shaw began celebrations at the Exploratorium science museum in San Francisco.

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