 World History Saturday, March 14, 1592. : Today is 'Pi Day', a celebration of the mathematical formula of Pi. Pi, in mathematics, is the ratio of the circumference of a circle to its diameter, and is represented by the symbol π. The ratio is the same for all circles and is approximately 3.14159.
March 14, written 314 in the USA date format, is an unofficial celebration for Pi Day derived from the common threedigit approximation for the number π: 3.14. It is usually celebrated at 1:59 pm, in recognition of the sixdigit approximation of 3.14159. Pi Day may be celebrated in a variety of ways. Groups of people, typically pi clubs, give thought to the role that the number π has played in their lives. Pi celebrants may hand out Pi Day greeting cards, devise alternative values for π, eat pi (pie), play pi (piņata), drink pi (Piņa Colada) or watch π (Pi (film)). Enthusiasts also note that the day happens to be Albert Einstein's birthday.
The ultimate pi day occurred on 14 March 1592 at 6:53am and 59 seconds. When written in Americanstyle date format, this is 3/14/1592 6:53.59, which corresponds to the first twelve digits of pi: 3.14159265359 (rounded off, as the absolutely exact value of pi cannot be computed). However, considering this was well before any kind of standardised world time had been established, and the general public had no concept of π, the occurrence likely went unnoticed.  
