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Remember pi? You now have more numbers to learn
Fri, 15th Mar 2019
FYI, this story is more than a year old

3.1415926… Pi is one of those magic set of numbers that not only a mathematical way to describe the ratio of the circle's circumference to its diameter, it must be one of the most recognisable sets of numbers in the world. Well, up to about four or five digits, at least.

Supercomputers have been put to work to calculate more and more numbers in the pi sequence to find out its precise value, but it's a song that never ends.And now a Google cloud developer advocate, Emma Haruka Iwao, has smashed the Guinness World Record for the most accurate value of pi.

With the help of Google Compute Engine, she calculated pi up to a whopping 31,415,926,535,897 digits. This is the first time the cloud has been used to calculate such a huge number. Google has published the computed digits of pi as disk snapshots that are freely available for anyone to use.

“Anyone can copy the snapshots, work on the results and use the computation resources in less than an hour. Without the cloud, the only way someone could access such a large dataset would be to ship physical hard drives.

How did Emma find herself in this position? She says it was a ‘pie-in-the-sky' (or should that be ‘pi-in-the-sky) idea.

Step 1: Find inspiration for your calculation

When Emma was 12 years old, she became fascinated with pi. “Pi seems simple—it starts with 3.14. When I was a kid, I downloaded a program to calculate pi on my computer,” she says. “At the time, the world record holders were Yasumasa Kanada and Daisuke Takahashi, who are Japanese, so it was really relatable for me growing up in Japan.

Later on, when Emma was in college, one of her professors was Dr. Daisuke Takahashi, then the record holder for the most accurate value of pi using a supercomputer. “When I told him I was going to start this project, he shared his advice and some technical strategies with me.

Step 2: Combine your ingredients

In order to calculate the most digits ever of pi, Emma used an application called y-cruncher on 25 Google Cloud virtual machines. “The biggest challenge with pi is that it requires a lot of storage and memory to calculate,” Emma says. Her calculation required 170 terabytes of data to complete—that's roughly equivalent to the amount of data in the entire Library of Congress print collections.

Step 3: Bake for four months

Emma's calculation took the virtual machines about 121 days to complete. During that whole time, the Google Cloud infrastructure kept the servers going, without any failures or disruption. If it did, it would have disrupted the calculation. When Emma checked to see if her end result was correct, she felt relieved when the number checked out. “I started to realise it was an exciting accomplishment for my team,” she says.

Step 4: Share a slice of your achievement

Emma thinks there are a lot of mathematical problems out there to solve, and we're just at the beginning of exploring how cloud computing can play a role. “When I was a kid, I didn't have access to supercomputers. But even if you don't work for Google, you can apply for various scholarships and programs to access computing resources,” she says.

“I was very fortunate that there were Japanese world record holders that I could relate to myself. I'm really happy to be one of the few women in computer science holding the record, and I hope I can show more people who want to work in the industry what's possible.

How will Emma celebrate? Word is, she might treat herself to a piece of pie.

“I like apple pie—not too sweet,” she says.