Mark your calendars! It is almost Pi Day! What is Pie Day you may ask? Well, it a bit of fun based on math. The number pi (the Greek letter π) is the ratio of the length around a circle (the perimeter) to the distance across (the diameter). So to calculate pi you just need to measure around the edge of a circle then divide by its width. The number you will get (depending on how well you measure) will be about 3.14. So just for fun people have started to call March 14th (3/14) Pi(e) day.