Math geeks and others celebrate Pi Day every March 14 . Pi , or roughly 3.14 , is the ratio of circumference to diameter of a circle . How do you celebrate Pi Day ? The Pi Day holiday idea started at the Exploratorium museum in San Francisco . Hide Caption 1 of 10 Photos:Photos: Celebrating pi day with math geek pals
Math geeks and others celebrate Pi Day every March 14 . Pi , or roughly 3.14 , is the ratio of circumference to diameter of a circle . The Pi Day holiday idea started at the Exploratorium museum in San Francisco . Hide Caption 1 of 10 Photos:Photos: Celebrating pi day with math geek pals