Do you know what today is? The mathematically inclined among you will instantly proclaim that it is, in fact, Pi Day. This impromptu holiday happens every year on 3/14 (like 3.14 at the beginning of pi). Of course this only works in the American date format, but let’s all look past that to celebrate this crazy mathematical constant together. Bonus: it’s also Einstein’s birthday!The dry mathematical definition of pi is the ratio of a circle’s circumference to its diameter. That’s cool, but what does it mean? If you take a perfect circle, no matter how massive, and divide its circumference by the diameter, you always get pi. Thus, a circle’s circumference is always 2π. This value is hugely important in physics and engineering.Because pi is an irrational number, it repeats forever. Some mathematicians have made it a challenge to continuously calculate more and more digits of pi. The current record for this noble endeavor is 10,000,000,000,050 decimal places, held by Alexander Yee and Shigeru Kondo. It took them 371 days to make the calculation with a dual-core Xeon PC running 96GB of RAM and 58TB in total storage.Here’s a visualization of one small part of that data. Each pixel in this image represents one digit of pi. Make sure to check out the interactive version as well.Maybe you didn’t plan ahead for the Pi Day festivities. Well, then maybe you’ll want to wait for Pi Approximation Day this summer. On July 22 (or 22/7 in the day-month format) we get the value 3.1428… it’s close enough.Pi Day was first organized by physicist Larry Shaw in 1988. He envisioned it as an excuse to walk around in circular rooms eating pies (which are round, so you can justify it). I think that sounds pretty good.Whether you’re just eating some pie, or building a giant pi domino spiral, we at Geek wish you the best Pi Day possible.