Depending on how much you love or loathe math, today might be a day to celebrate or forget. It is March 14, or 3/14, and is better known in math circles as Pi Day.It was first thought up by the physicist Larry Shaw while working at the San Francisco Exploratorium in 1988. He wanted to celebrate the mathematical constant we all remember from school: 3.14159. But how do you get people to celebrate a number? Simple, you mark the day by offering up an excuse to eat delicious pie.If you’ve never heard of Pi Day before, you may be surprised to find how popular it is. Several universities celebrate the day, with MIT being a standout example as they mail out applicant decision letters today, but do so at 6:28pm. This is known as Tau Time, as tau is twice as large as pi and a major competitor to the crown pi holds in the world of math.It’s also fitting that today is Albert Einstein‘s birthday, so many double celebrations happen including pi reciting competitions. However, I prefer Larry Shaw’s original idea for how to celebrate the day: we all march around in a circle while eating lots of delicious pie. As well as offering up an opportunity to eat, any kids taking part are sure to learn what pi is and how to remember the first 6 digits of it with a rhyme:Cosine, secant, tangent, sine! 3.14159If your main reason for celebrating Pi Day is as an excuse to eat pie, you’ll also be glad to know there’s a second celebration on July 22. That’s Pi Approximation Day as the fraction 22/7 is a common approximation of pi.And there’s one final use to point out for pi outside of math. If you ever need to get the attention of a room full of scientists or mathematicians, The Simpsons‘ Professor Frank has this top tip to offer:Thanks to Wikipedia for background information.