Mid-March is chock full of special days (as well as snow, if you live in upstate New York, which is another story entirely.) While most people focus on St. Patrick’s Day on March 17–the day most wardrobes and some rivers turn green–March 15 marks the Ides of March, most meaningful, perhaps, to Julius Caesar. Mathematicians start the festivities early, though, commemorating the day that evokes one of the most meaningful and magical numbers of all: pi.
What makes pi (or π) so special? The number 3.14159… is the ultimate irrational number, a non-repeating, non-terminating decimal that pops up in all kinds of math and physics formulas. Pi serves as a staple in circle geometry, representing a mathematical constant that is the ratio of a circle’s circumference to its diameter.
Obviously, pi is impressive and worthy of celebration, but how does one actually celebrate Pi Day? Even if you don’t feel compelled to solve circle formulas all day, you can still enjoy increasingly common pizza and bakery specials. Make or eat as much pie as you want, and increase your own circumference. Happy Pi Day!