The international standard date convention puts the month before the day and is typically used by citizens of the US.
This allows American mathematics enthusiasts to declare today, 3/14, Pi Day. Pi is the symbol for the ratio of the circumference of a circle to its diameter, Pi = 3.1415926535, and is a number beloved of number-lovers everywhere, including such luminaries as Archimedes and Leonardo da Vinci. If you'd like to mark the occasion you could purchase a copy of David Blatner's Joy of Pi(Penguin Press Science) and enjoy Pi trivia, Pi-inspired cartoons, poems, limericks, and jokes, as well as learning the value of Pi to the first one million digits. Alternatively you could buy, bake or consume a pie, such as the one pictured.