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Emma Haruka Iwao with digits of pi
Google’s Emma Haruka Iwao dashes across a whiteboard to write down the first digits of pi. She used Google Compute Engine, powered by Google Cloud, to calculate pi to an accuracy of 31.4 trillion digits. (Google via YouTube)

What’s the best way to celebrate Pi Day? That’s the geeky holiday that takes place on 3/14 … in other words, today. For some, it’s a day for baking geeky pies, or getting a $3.14 deal on slices of pizza. For Google, it’s a day for breaking a world record, by calculating the irrational number’s value to 31.4 trillion digits of precision.

31,415,926,535,897 digits, to be exact.

Pi enters into every walk of life, if that walk happens to be circular. On one level, it’s the ratio of a circle’s circumference to its diameter. On another level, it’s a mystical number to contemplate, because the digits just go on, and on, and on …

Physicist Larry Shaw invented a ritual to celebrate that mystical value, and that ritual was first celebrated at San Francisco’s Exploratorium for the first time 30 years ago. It involves walking in a circular procession on 3/14 at 1:59 p.m. (in honor of 3.14159), singing happy birthday to Albert Einstein, and reveling in a pie feast (fruit and/or pizza). The ritual is celebrated at the Exploratorium to this day.

Down the road, Google took a more literal look at the reason for the season: Under the leadership of cloud developer advocate Emma Haruka Iwao, the pi-calculating team focused the power of the Google Compute Engine and 25 Google Cloud virtual machines on an application called y-cruncher.

The task required 170 terabytes of disk storage space, 10 petabytes’ worth of data reads and 121 days of calculation. But in the end, thanks to an algorithm known as Chudnovsky’s formula, the team got the job done last December. The result beat the previous record-holder, as judged by Guinness World Records, by almost 9 trillion digits. Just speaking all the digits aloud would take more than 330,000 years.

For the record, here are the last 97 digits of the result:

6394399712 5311093276 9814355656 1840037499 3573460992

1433955296 8972122477 1577728930 8427323262 4739940

For the details about how the job was done, check out the postings to mathematician Alex Yee’s Number World blog, the Google Blog and the Google Cloud Blog.

To celebrate, Iwao and her team are thinking about having a piece of pie. “I like apple pie — not too sweet,” she said.

If you’re similarly inclined, there are pie specials today at Pagliacci Pizza (two for $3.14, or a $3.14 BOGO deal), Whole Foods ($3.14 off normal pie prices) and other food stores. And Pi Day is always a big day for the Pie bakery in Seattle’s Fremont neighborhood (“There will be a line!”).

Finally, here’s a smorgasbord of Pi Day tweets for your enjoyment:

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