In the science-fiction stories of a few decades ago, there was a definite way to crash a nasty computer: get it to calculate the value of pi. Since pi is an “irrational” number, it never ends — the number of digits just goes on and on and on.

Pi is the ratio of a circle’s circumference to its diameter. Although it doesn’t have an exact value, it’s approximated as 3.14. And since today is 3.14 on the calendar — the 14th day of the third month — it’s Pi Day.

Scientists, mathematicians, and others have been using pi for millennia. It applies not only to circles, but to spheres, cones, cylinders, and other objects. It makes it possible to calculate surface area, volume, and other measurements. That’s handy for astronomers as they study stars and planets.

The concept of pi has been around for thousands of years. Egyptian architects used it to build the pyramids of Giza, for example. Their work was based on measurements. Mathematicians began calculating the value of pi around 2,000 years ago.

The name “pi” was first used in the 1600s. And it didn’t become popular until the following century. It was picked because it was the first letter of the Greek word “perimetros,” which means perimeter or circumference.

Over the centuries, scientists have calculated the value of pi with ever greater precision. And supercomputers have allowed them to add even more digits. So far, the record is about 31 trillion — with no end in sight.

Script by Damond Benningfield

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