Today 22 July Pi Approximation Day

Pi Approximation Day is observed on July 22 (22/7 in the day/month date format), since the fraction 22/7 is a common approximation of π, which is accurate to two decimal places and dates from Archimedes

Good Article about PI approximation

http://www.huffingtonpost.com/2012/07/21/pi-approximation-day-_n_1693199.html

http://www.bendigoadvertiser.com.au/story/4044914/world-celebrates-the-ongoing-mystery-of-pi/?cs=82