By John Novitsky of Woodside, an engineer and businessman in Silicon Valley for 33 years.

Congratulations Almanac readers. As you read this article, there won't be another "Pi Day" like this for 1,000 years. It's a celebration of one of the most famous irrational numbers in history.

Pi is a constant, defined as the circumference of a circle divided by its diameter. This year is special; the first 10 digits of Pi are 3.141592653. Expressed as a date and time, that's this Saturday, 3/14, year 2015, at 9:26:53 in the morning (though some quibble that it should be at 9:26:54 a.m. due to rounding).

The earliest known written representations of Pi appeared on clay tablets from Babylon (circa 1900 B.C. to 1600 B.C.), and on a papyrus scroll from Egypt (1850 B.C.).

The Greek mathematician Archimedes defined Pi more accurately back in 250 B.C. It took 1,000 years before mathematicians developed better tools to improve Archimedes' calculation.

Today, supercomputers have calculated Pi out to 13.3 trillion digits; no pattern repeats. People try to memorize Pi; the record is over 67,000 digits.

Most people consider the first well known "Pi Day" celebration to have been organized at the San Francisco Exploratorium in 1988.

Here in Silicon Valley, and around the world, many engineers and mathematicians celebrate Pi day by eating pie, and telling math jokes with their scientific friends.

Generally, the more bad jokes you can squeeze into your pie recipe, the better. (Slice up 3.14 apples, bake till a golden mean, and so forth.) Could be a fruit pie, a meat pie, a pizza pie, an ice cream pie, an insect pie: it's all good.

MIT notifies its students of acceptance of admission on Pi day (3/14), at Tau time (6:28 p.m.) to honor both rival numbers. (Tau day celebrations are already being planned for 6/28 2031. Most Tau Day celebrations won't be as "tasteful," since eating a Tau is ... well ... less well defined.) 3/14 is also Albert Einsten's birthday.

Whether you are a high school student eagerly awaiting your MIT admission notification this Saturday evening, or hanging out with your slide rule carrying friends groaning over bad puns but eating good pies, Happy Pi Day.

## Comments

MarieWoodside: Skywood/Skylonda

on Mar 14, 2015 at 10:07 am

Marie, Woodside: Skywood/Skylondaon Mar 14, 2015 at 10:07 am

Don't you mean that there won't be another Pi Day like this in ONE HUNDRED (not one thousand) years? In 2115, the date will also be written as 3/14/15.

Pot PieMenlo Park: Sharon Heights

on Mar 14, 2015 at 11:40 am

Pot Pie, Menlo Park: Sharon Heightson Mar 14, 2015 at 11:40 am

100 years.

I love that the Exploratorium gets the recognition.

Beef pie, followed by cherry pie, thanks. And you?

whateveMenlo Park: Central Menlo Park

on Mar 14, 2015 at 5:01 pm

whateve, Menlo Park: Central Menlo Parkon Mar 14, 2015 at 5:01 pm

So John, What is it 1,000 or 100 years? If it's actually 100 years please correct the article. Thanks. Wouldn't want any pies tossed.

johnWoodside: other

on Mar 15, 2015 at 8:39 am

john, Woodside: otheron Mar 15, 2015 at 8:39 am

Readers- I was the author of the article. I asked several of my engineer, mathematician and scientist friends, "when is the next year this kind of Pi day will occur?" They were spilt down the middle: 50% said in 1000 years (due to the zero in the hundreds place), and 50% said in 100 years. The remaining 50% of mathematicians said "it depends". (a little Pi day humor there). Roughly the same proportions for the 9th digit, i.e. "exact seconds". Half ignored the 10th digit of Pi, half rounded up to make even. The remaining half quibbled about "leap seconds", rotational speed of the Earth and so forth. We all agreed - even the mathematicians- on two things: 1) we can't wait until the Pi year celebrations in year 3141 - the parties will be spectacular!, and 2) we all like pie.

Pot PieMenlo Park: Sharon Heights

on Mar 15, 2015 at 9:07 am

Pot Pie, Menlo Park: Sharon Heightson Mar 15, 2015 at 9:07 am

>>> 50% said in 1000 years (due to the zero in the hundreds place), and 50% said in 100 years. The remaining 50% of mathematicians said "it depends".

150% ????

Those math guys. Always full of laughs.

;-)