March 14 is Pi Day. No, that is not a typo. It means that 3/14 is the day when people the world round (some people, anyway) celebrate the invention of that wonderful number, 3.14, known as Pi. (Actually, you can roll Pi out to 3.141593 and then keep adding numbers infinitely to the right.)

Need a brush-up? Okay, here we go.

Pi is a number that is equal to the value of the ratio between a circle's circumference and its diameter. Just when Pi was discovered is anybody's guess, but there is evidence that the ancient Egyptians already knew about it in about 2,500 B.C., when they constructed the Great Pyramid at Giza. The neat thing about Pi is that it is the same for any circle - whether it's your wedding ring or a manhole cover or a crop circle that just appeared in your back yard.

If you want to analyze a circle, Pi is an incredibly useful ratio. Circles, you know, are ornery geometrical shapes. If you want to know the area of a square, you simply square the length of one side, and you know it. Even triangles aren't that tough. But circles are a lot tougher - as you might have noticed, they have no sides.

But armed with Pi, you can find out just about anything you need to know about any circle, by using one of the following formulas:

To find the area of a circle, the formula is Pi x R2. (Pi times the radius squared.) In everyday English, that means that you measure the width of a circle at its widest point (the diameter), divide that in half (that tells you the radius), and multiply that times Pi (3.14). Presto! You now know the area of your banana cr?me pie, or any other circle.

To find the circumference of a circle, the formula is Pi x D. (Pi times the diameter.) In other words, you measure the width of the circle at its widest point (the diameter) and multiply that times Pi (3.14). Viola! You now know the distance you will have to go if someone makes you walk around the world's largest pizza, 30 feet across, that was just baked for your state fair.

Learning More about Mathematics

If it's been a while since you studied mathematics - or if you would like to study math for the first time - maybe this would be a good time to take a college-level math course online that can teach you the basics.

In addition to Pi, you might even learn about the Pythagorean Theorem, which can help you analyze triangles.

Want another quick review? Pythagoras, who invented that theorem, was a Greek mathematician who lived about 500 B.C. According to legend, his mathematical discoveries were so powerful that he figured out a way to appear in two different cities simultaneously, where he would give speeches to people. You might not discover how to do that in your mathematics course. But one thing for sure. You will discover a way to have your Pi and eat it too.

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Enroll in one of our College Algebra, Precalculus, or Statistics online college courses between 3/9/10 and 3/20/10 and save $31.42 (Pi x 10 - rounded). Just enroll in a course then call our customer support department and tell them you want your Pi Day Blog discount and they will give you a one-time $31.42 refund on your monthly subscription fee. Go ahead and celebrate Pi Day - it is fun, educational and you can save some money...