If you recognize the number or symbol in the graphic, then you might be among those who will be looking forward to March 14 when National Pi Day [1] is celebrated.

March 14 is Pi Day, a day to celebrate the mathematical constant pi (π) (and to eat lots of pie).

Why March 14? Pi Day is celebrated around the world, but in countries that follow the month/day (m/dd) date format, including the United States, the digits in the date, March 14 or 3/14, are the first three digits of π (3.14). Pi Day was founded by U.S. Physicist Larry Shaw in 1988 and first recognized at the Exploratorium [2] family museum in San Fransisco, where Shaw worked.

Coincidentally, this is also Albert Einstein’s birthday [3]. Seems fitting, somehow.

**Pi Day has become an international holiday, celebrated live and online all around the world.**

You can celebrate Pi Day at 1:59 PM local time on March 14. This time represents the next three digits of pi: 3.14*159*. Take a minute to acknowledge pi in whatever way you see fit at that moment. During this minute, you can cheer wildly, or even have a countdown the minute before leading up to "pi minute."

Do a pi mile run. Run 3.14 miles (5.05 km), which is just a tiny bit longer than a 5K. You can take this a step further by organizing a pi mile run with friends or colleagues.

For the less athletically inclined, have a pie baking competition, or a pie eating challenge, or just enjoy a slice of pie.

The entire month of March 2014 (3/14) was observed by some as "Pi Month". In the year 2015, Pi Day had special significance on 3/14/15 (mm/dd/yy date format) at 9:26:53 a.m. and also at p.m., with the date and time representing the first 10 digits of π. It may take a century for Pi Day to have that special oomph again, but science and math fans can enjoy Pi Day every year for the rest of time.

**Pi Day Fun Fact:**** Star Trek’s Mr. Spock knew the value of pi. In the “Wolf in the Fold” TV episode, Spock thwarts an evil entity inside the Enterprise’s computer system by ordering it to “compute to last digit the value of pi,” which can never be computed.**