Today is ∏ day (for the lack of similar symbols!), and is celebrated because of its relevance with the date 3/14. 
Pi, approximately 3.14159, is the mathematical constant that represents the relationship between a circle’s diameter and circumference. Google is celebrating Pi day by its Google doodle.
Some people memorize the Pi constant for fun and the current record is 100,000 numbers. Pi was calcutated to run into some trillions so the competition is still open.
Lets all yay to Pi.