March 14 might be the only day of the year named to honor a math concept. Pi Day might be a good excuse to have a big piece of pie while doing your math homework. There are even jokes about pi – and there aren’t very many math jokes (and maybe no good math jokes).

This is one of the oldest pi jokes: Mathematicians say, “Pi r squared.” Bakers say, “Cakes are square. Pies are round.”

One more joke: What is Pi Day’s official animal? The pi-thon.

**Pi – 12,000,000,000,000 Digits and Counting…**

The value of pi is 3 plus an infinite number of digits after the decimal point: 3.14159265358979323846… As you may have noticed, Pi Day is March 14 because the first three digits of pi are 3.14. In common usage, people often shorten pi to 3.14159.

Pi has intrigued people since the Babylonians began working on computing pi about 4,000 years ago. It took 3,500 years before mathematicians were able to calculate the value of pi to 3.1415926536. By 1996, pi had been computed to over 400 billion digits. Computers have now calculated at least 12 trillion digits for pi.

**Pi (π)** **is Very Useful for Solving Geometry Problems Involving Circles and More… ****circle**

Pi (symbolized by π) refers to the ratio between a circle’s circumference and its diameter. The circumference of a circle is the distance around the circle while the diameter is the distance from one edge to the other, passing through the center.

Pi is used to calculate the area and circumference of a circle.

Pi is also useful for finding the volume and surface area of a cone, cylinder and sphere.

There are applications for pi in the fields of statistics and probability.

Pi is important in determining normal distributions and prime number distributions.

**Two Useful Formulas**

**The area of a circle: A = πr ^{2}**

^{ }

r = radius or the distance from the center of a circle to the edge

**The volume of a cylinder: V = πr ^{2}h **

r = radius h = height

Calculate the area of the base of the cylinder (which is the area of a circle or πr^{2}) and multiply that by the cylinder’s height (h).

**Pi – Weird and Wonderful**

Pi is a mathematical constant. All of the digits of pi may never be known, but the known digits never change.

Pi is also described as an irrational number since the number of digits is infinite.

Pi can be approximated as the fraction 22/7.

Pi is the 16^{th} letter of the Greek alphabet.

Literary nerds invented the pi language “Pilish.” The book “Not a Wake” is written in Pilish. The number of the letters in the words match the digits of pi.

To write in Pilish: 3.14159… = first word has 3 letters, second word has 1 letter, third word has 4 letters, fourth word has 1 letter, fifth word has 5 letters, sixth word had 9 letters etc. Try it out for yourself!

The record for memorizing the most digits of pi is held by Chao Lu of China. He won a place in the Guinness World Records by reciting from memory 67,890 digits in 2005.

Pi Day or March 14 is also Albert Einstein’s birthday.

Pi is unique in mathematics. When studying geometry and other branches of mathematics, pi is an important and useful concept. There are few things that never change over time, but pi is one of them.