Pi Day means cheap pies - and beer - at District of Pi Buy any District of Pi deep-dish pizza today and get a second for $3.14. Or is that $3.141592? (Bill O'Leary/The Washington Post) The nerdiest holiday of the year? My vote goes for Pi Day, celebrated every March 14 because 3/14 looks a lot like 3.14, the first three digits of the mathematical contstant used to help determine the circumference of a circle. There are a number of ways to celebrate, from the Maryland Science Center to a pie festival in Mount Pleasant, but I'd suggest heading to the District of Pi pizzeria on F Street NW, which honors its namesake theorem with a slew of Pi Day deals. Buy any pizza and get a second for $3.14. Pints of the house beer, brewed by St. Louis's award-winning Schlafly brewery, cost $3.14 all day. And at 6 p.m., the bar will have a Pi memorization contest: Anyone who can recite at least 50 digits of Pi wins a prize; the person who can remember the most takes home a $100 gift certificate. Need more inspiration for this gorgeous afternoon? Take a look at our list of the area's best pies, or see the Buzz's suggestions for local events. The Style Blog has a roundup of ways to celebrate, which range from pie crust recipes to math-themed raps.