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:

The excitement of #PiDay is upon us! This year’s #NASAPiDayChallenge features four planetary puzzlers that show how pi is used for our missions — such as sizing up a storm on Jupiter & blasting ice samples with lasers! Take on the challenge: https://t.co/ZJ0rttG0WY pic.twitter.com/XojhMuE7lK

— NASA (@NASA) March 14, 2019

Happy #PiDay! This strip was first published on October 19, 1963. pic.twitter.com/pc2BHsi3zU

— SchulzMuseum (@SchulzMuseum) March 14, 2019

Albert Einstein gets a #PiDay birthday shout-out from space https://t.co/va49xZcL1H pic.twitter.com/N7aiuGXxLS

— CNET (@CNET) March 14, 2019

🚀🚀🚀

It's launch day for @Astro_Christina and @AstroHague!

🚀🚀🚀

Lift off on π day at 3:14 pm ET on their way to the @Space_Station

🚀🚀🚀https://t.co/UwdHEDYYZv pic.twitter.com/JDkU6PbTC0— Stephanie (@schierholz) March 14, 2019

1. I know what you’re thinking: “Dan, I enjoyed your ‘7 facts about Pi’ list (https://t.co/XfRRtmSS8g), but I’d like to explore pi further!” Excellent – let’s talk about pi!! Let’s start with that website that lets you search the first 200 million digits of pi… (cont’d) #PiDay

— Dan Falk (@danfalk) March 14, 2019

2. This Pi Search website (https://t.co/22678BQXkP) is run by David Andersen, a computer scienctist at Carnegie Mellon Uni. in Pittsburgh. Let’s start by looking for amusing strings, like 01234567 – turns out it pops up a bit past the 112-million decimal place… #PiDay

— Dan Falk (@danfalk) March 14, 2019

6. Now, when you get to the 172,330,850th decimal place, you suddenly find “00000000”! Resist the temptation to run through the streets yelling “Pi is a rational number after all! The mathematicians were wrong!” ;) Because after the eight zeros, the chaos resumes… d’oh!! #PiDay pic.twitter.com/y9AvpDCCH9

— Dan Falk (@danfalk) March 14, 2019

10b. By one estimate, we can never get beyond the 10^51st digit (that’s 10 to the power of 51, or a thousand trillion trillion trillion trillion) before the so-called heat death of the universe. So this #PiDay let's enjoy the >22 trillion decimal places that we've got so far. :-)

— Dan Falk (@danfalk) March 14, 2019

Happy Pi Day, featuring the best skyline in the world! 💛

Whether it's 3.14 or any other day of the year, this pie by Seattle's own The Bee and the Baker is a piece of perfection, and we are not biased. 😍 #pieday #piday #seattleskyline #bestpieever pic.twitter.com/GA211SI9Ts

— Space Needle (@space_needle) March 14, 2019

Happy #PiDay! Entering to win 1 of 5 roundtrip flights we're giving away is as easy as pie! 🥧

To enter:

1. Follow @AlaskaAir

2. Let us know what city you'd travel to for your favorite piece of pie!

3. Include the hashtag #PiDay and the emoji ✈Rules: https://t.co/MCPlTzxGEZ pic.twitter.com/lniSOZQZgV

— Alaska Airlines (@AlaskaAir) March 14, 2019

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