Pi is equal to 3.14, and 3.14 is usually used to approximate pi. The decimal number 3.141592653 is sufficient for general calculations. Even engineers and physicists who want to do more precise calculations need to take the value to at most a few hundred decimal places.

The fact that π is an irrational number, i.e., that it cannot be expressed as the ratio of two integers, was proved by the German scientist Johann Heinrich Lambert in 1761.In 1882, Lindemann proved that π is transcendental, i.e., that it is impossible for π to be the root of a polynomial of any integer coefficient.

The transcendental nature of pi negates the possibility of the old ruler graphing problem of turning circles into squares, since all ruler graphing can only yield algebraic numbers, and transcendental numbers are not algebraic numbers.

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International Pi Day dates back to March 14, 1988, when Larry Shaw, a physicist at the Science Museum in San Francisco, who organized museum staff and participants to do 3 and 1/7 laps (22/7, one of the approximations of π) in a circle around the museum monument and eat fruit pies together. The San Francisco Museum of Science has since carried on the tradition, celebrating the day every year.

In 2009, the U.S. House of Representatives formally passed a non-binding resolution designating March 14 as Pi Day. The resolution recognizes that math and natural sciences are an interesting and integral part of education.

And learning about pi is a fascinating way to teach children about geometry and engage them in the natural sciences and mathematics. ...... Pi equals approximately 3.14, making March 14 the most appropriate day to observe Pi Day.