What started out as a small annual tradition at San Francisco's Exploratorium in the late 1980s, has turned into a widely recognized and good-spirited national holiday celebrating the mathematical symbol for Pi. The symbol (π) represents the ratio of the circumference of a circle to its diameter, which is roughly 3.14—however the number has been successfully carried out to more than a trillion decimal places.
It's actually a national holiday, named as such by congress back in 2009. And, this year the date takes on special significance because Pi Day (3.14) falls within Pi Month.
Members of the Cal Poly Math Club in San Luis Obispo helped to mark the holiday by hiking up a hillside to the university's 50x30 foot landmark "P" and placing a lowercase "i" next to it. The temporary "Pi" can now be seen throughout the campus area.
"It's important to know that the number exists because it's important when dealing with math of circles, and that applies to physics, statistics, theoretical math and more," said Lumin Sperling with the math club. "I think that people like that it goes on forever with no pattern. It's just very interesting."
But it's not just math fanatics that get excited about National Pi Day—those who love the similar sounding pastry deliciousness of "pie" also get into the act. San Luis Obispo's Apple Farm Inn—famous for pies—celebrated this year by knocking $2 off their signature pies, and offering samples as well.
Up the coast, management at Linn's of Cambria told KCBX they donated pies to local schools as a teaching aid, but other than that we're told "every day is pie day" at Linn's.
At Simply Pies in Santa Barbara, workers have seen a very "Pi Day-spirited crowd" today, according to Barbara (no last name given).
"We're running low on pies right now," Barbara told KCBX at 3:00 p.m. "It's a lot of fun, everyone is really excited to celebrate the day."