For all of you nerds, pie-in-the-sky dreamers and circular reasoners (and anyone who's been accused of being, or wants to be, any of those), your day has come: **Pi Day**, on** ****March 14**. In 2014, Pi Day turns 26.

A quick refresher: Pi, the ratio of a circle's circumference to its diameter, is **3.14159....** It's an irrational, infinite number; it has been calculated to 10 trillion decimal places so far, and each digit appears as often as any other digit. There are no patterns or repeating sequences among the digits, so pi seems to be statistically random.

**San Francisco** has a unique claim to Pi Day--it was born in our very own Exploratorium, the brainchild of physicist Larry Shaw. In 1988, Shaw got his Exploratorium colleagues to help build a pi shrine, circle around it and eat pie. The U.S. House of Representatives in 2009 passed a non-binding resolution recognizing March 14 as **National Pi Day**. The reasoning was simple: "Whereas since 1995 the United States has shown only minimal improvement in math and science test scores" and "America needs to reinforce mathematics and science education...to compete in a 21^{st}-century economy," our reps figured that designating and promoting Pi Day might nudge those scores up. It's a nice coincidence that March 14 is Albert Einstein's birthday.

Pi Day is now an international phenomenon. In San Francisco, here are some public celebrations in 2014 of the homegrown holiday. On your own, you can try the Exploratorium website's pi puzzlers, read or watch *Life of Pi*, watch *Pi*, memorize as many pi digits as you can, walk, spin and think in circles, eat pie, and be irrational for the day.

**26th Annual Pi Day***March 14, at 1-3:30 pm*

Come to the birthplace of Pi Day. The homage includes a pi procession to the Pi Shrine, demos and talks about pi, tossing of pizza pie dough and servings of pie. *At the Exploratorium, Pier 15, San Francisco 94111. Free.*

**Pi Day Puzzle Party ***March 14, at 7 pm *

Exercise your gray matter in a fun and lively competition to solve math and logic puzzles. You can fly solo or with a crew of up to six people; come with crew mates or form a team once you arrive. Bring pencils and scratch paper, and for brain power, chomp on food truck offerings. Hosted by math guy Wes Carroll and organized by Ask a Scientist.*At the SoMa StrEat Food Park, 428 11th St., San Francisco. Free.*