Pi Day, Pi Day, gotta get down on Pi Day.
Saturday marks "Pi Day," the one day each year the calendar's digits match up with "pi" or "π," the irrational number that expresses the ratio of a circle’s circumference to its diameter. In other words, March 14 (or 3/14) matches 3.14, the shortened number for pi.
The date is particularly exciting this time around, as the digits in the year (2015) line up with the next two digits of pi, "15."
Those looking to kick their veneration up a notch should be especially rowdy at 9:26 (a.m. or p.m.), which would correspond with the next three digits of pi (3.1415926), which has an infinite number of non-repeating digits.
If you're looking to celebrate with other revelers, fear not: Pi Day celebrations span the globe. There are events all across the U.S., some of which we've listed here:
Ring in Pi Day with free admission to The Exploratorium, which the Los Angeles Times says first celebrated (and therefore may have "invented") the holiday 27 years ago.
Hit up Delicious Pizza for a free slice of pie at 9:26 p.m.
Run 3.14 miles around beautiful Washington Park. The park is only 2.35 miles around, so you'll need to complete an extra third of a lap to pay appropriate homage to the math Gods.
Chicago's Museum of Science and Industry will give a free slice of pie or pizza to the first 314 visitors. Those who follow will be eligible to buy slices of both at a discounted rate of -- you guessed it -- $3.14.
Join hundreds of other revelers in Madison Square Park at 9:26 p.m. to watch -- and perhaps even take part in -- a glow-in-the-dark demonstration on the meaning of pi coordinated by the National Museum of Mathematics.
You can always celebrate responsibly at home with a slice of your favorite pie, be it one topped with cheese, or the kind filled with apples -- or perhaps both. (Hey, it's Pi Day, go crazy!) Oh, and wish Albert Einstein a happy birthday while you're at it. The celebrated physicist was born on March 14, 1879.