##### Wednesday, March 16, 2016 12:18 pm

**No forks needed to enjoy slice of Pi Day**

**Frank Gray
**

Saturday is going to be a special day.

For the only time this century, it will be Pi Day. No, not Pie Day, but Pi Day, as in day, as in 3/14/15.

And it’s not just Pi Day but a super Pi Day. So get up early Saturday to rejoice in the glorious moment at 9:26:53 a.m. when it will be 3/14/15 9:26.53. That’s pi figured out to nine digits.

If you are a reporter or cook, you probably haven’t paid a lot of attention to pi since high school, so if you’ve forgotten, pi is the ratio between the diameter and the circumference of a circle.

It might not seem like it, but pi is all around us, says Adam Coffman, a mathematics professor at IPFW. It is used to calculate the surface of a sphere, the volume of a sphere, the volume of a cylinder and lots of other things.

Albert Einstein used it liberally in his calculations, and it’s used today in computer science to compress files, in digital signaling, in our GPS systems and in all kinds of iPhone apps, Coffman said.

When it comes to studying pi, though, Coffman said, there are only about 100 people in the world who do that, just ponder pi.

The value of pi was first calculated by Archimedes as a fraction, 22/7. For centuries, its value hadn’t been calculated beyond seven digits.

In the 1700s, Coffman says, one mathematician, using a pencil and paper, calculated the value of pi out to 750 digits, but he made a mistake along the way, so the last few hundred were all wrong.

There actually are pi deniers, Coffman said, people who think everybody from Archimedes to modern mathematicians are wrong. In 1897, a self-styled scientist with his own ideas about the value of pi and other things offered to provide a mathematics curriculum he had designed to the state for free, and the Indiana House happily said yes. It was only then that other mathematicians started pointing out that his value for pi was all wrong, as were a bunch of other calculations. The Senate never took up the issue, so the students of Indiana were spared being taught a bunch of nonsense.

Today, computers have calculated the value of pi out to 12 trillion digits, a number so big you need a huge computer just to store the numbers.

Why do they do that? Well, Coffman said, you never know what you are going to find in the next trillion digits, plus, pi can be used to test computer programs to see whether they have flaws.

In reality, you don’t need that many digits in practical use. For example, if you know the diameter of the visible universe and you want to calculate the circumference of the visible universe, Coffman said, and if you use the value of pi figured out to 45 digits, you could calculate the circumference of the visible universe down to the diameter of a proton. That’s close.

So how should you celebrate Pi Day?

What better way than to memorize the value of pi, Coffman said. It’s 3.141592653897932383626433. We’ll stop there.

If you want to set a record for memorizing pi, it will take some work. Some guy in China memorized it out to 67,890 digits. Sounds like a fun guy.

Frank Gray reflects on his and others’ experiences in columns published Sunday, Tuesday and Thursday. He can be reached by phone at 461-8376, fax at 461-8893, or email at fgray@jg.net. You can also follow him on Twitter @FrankGrayJG.