Why pi? Beautiful in its simplicity, pi (pi = periphery) is the relationship between the perimeter of a circle (the circumference) and the distance across that circle (the diameter). For any circle, the principle is without exception universal — meaning it's always the same whether it be applied to a merry-go-round, a dinner plate, or a bicycle wheel.

For years the ancient Greeks struggled with rational numbers (those that could be written as a simple fraction) to arrive at the concept of pi. It was only later discovered that pi is an irrational number. Not crazy, mind you, but it does go on for infinity and can't be corralled into a corner.

Today, no one exactly knows who came up with the recipe for pi, but the symbol for pi was first used in 1706 by William Jones,
and later made popular by Swiss mathematician Leonhard Euler
in 1737.

Since then, pi has always been an underappreciated concept -- except for physicists and mathematicians who truly admire its beauty.

To make up for pi's shabby treatment, the first Pi Day was held at the San
Francisco Exploratorium in 1988 when visitors were invited
to participate in Pi-related antics and activities. Later,
all were invited back to a celebration to be served - you
guessed it - a slice of apple
pie.

Today,
one of the museum's
on-site physicists the "Prince of Pi" Larry Shaw, is duly recognized as the founder of Pi Day.

3.14 ways to celebrate Pi Day

Throw a pi party! Create
homemade invitations with colorful construction paper and use a compass to decorate the front cover with circles. Add a headline inviting friends to "Drop by to say pi!"

Decorate
with pi symbols, or designate the diameter on everything round
(clocks, area rugs, plates) and, of course, serve lots of
round foods — like pizza pie, quiche, fruit pies, donuts,
and pi-neapple rings.

Arrange
a sing-along of Pi
Day songs, play
Pi day trivia, or sponsor a contest to see who can memorize
the most digits of pi, i.e., 3.14159265358 with the winner
awarded a freshly baked... well, you know.

Think
.

Pieces of Pi Day around the Web:

Pi Day - The "official" Pi Day site with an extensive history and background of the irrational number with related YouTube
videos, Happy Pi Day e-cards, along with t-shirts and other Pi Day swag in the online shop.

Pi
Day - Wikipedia - Fun facts, historical tidbits, including
related photos and resources.

How
to Celebrate Pi Day - WikiHow tips with food ideas,
creating Pi Day atmosphere, making decorations, hosting games
and activities.

Pi Day Pinata! - Step-by-step instructions for making a Pi Day party pinata, with photos and materials list.

Pi
Day E-Cards - More than a dozen ways to wish friends and family a Happy Pi Day.