Happy Pi Day! Don't forget to wear your Pi Day t-shirt! March 14 is celebrated as Pi Day because the date, 3/14, is the first three di...  ...ause the date, 3/14, is the first three digits of pi , the ratio of a circle's circumference to it...

[http://youtu.be/x4kyFKyCMv0] (YouTube link)Once a...  ...e again the date is 3/14, known affectionately as Pi Day, a holiday in which to pay homage to the rati...  ...e ratio of a circle to its diameter. To celebrate Pi Day, Brady Haran of Numberphile produced this vid...  ...g Matt Parker measuring a big circl...