Pi DAY! by: Alyssa Varga

What is Pi? What is pi ( ) ? Who first used pi? How do you find its value? What is it for? How many digits is it? By definition, pi is the ratio of the circumference of a circle to its diameter. Pi is always the same number, no matter which circle you use to compute it.

What is the history of Pi? Pi is a very old number. We know that the Egyptians and the Babylonians knew about the existence of the constant ratio pi, although they didn't know its value nearly as well as we do today. They had figured out that it was a little bigger than 3; the Babylonians had an approximation of 3 1/8 (3.125), and the Egyptians had a somewhat worse approximation of 4*(8/9)^2 (about ), which is slightly less accurate and much harder to work with. The modern symbol for pi [ ] was first used in our modern sense in 1706 by William Jones.

The history continued… Even before this Pi was discovered The first record of an individual mathematician taking on the problem of π (often called "squaring the circle," and involving the search for a way to cleanly relate either the area or the circumference of a circle to that of a square) occurred in ancient Greece in the 400's B.C.

How can we use pi? Pi is used anytime there is a circular (as opposed to linear) geometry involved. Examples include circles, cylinders, spheres, and other curves. Pi is used in math to define the ratio of circumference to the diameter of a circle. So if you are looking for the circumference and have the diameter multiply it by pi to get the circumference. Pi is an irrational number which is a ratio of the circumference of a circle to its diameter. An irrational number is a decimal that does not repeat nor terminate.

A real-world problem People everywhere use pi. Circles are everywhere in the world! Tires, Pizzas, doughnuts, pie, oranges, basketballs, and plates. Pi can be used in a real world problem when a tire rim maker makes rims. They have the circumference but need to figure out the radius to create the perfect connections.

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