Today is March 14, or, as it's better known to mathematics enthusiasts, Pi Day!
Pi is an irrational number, and has an infinite number of non-repeating decimal places. Currently, over 1 trillion digits of pi have been calculated, but we will never reach the end. However, for most applications, 3.14 is a good enough approximation. As March 14th is abbreviated 3/14, we celebrate this handy constant.
So have a slice of pie, and a happy pi day!
To learn more about Pi, check out http://www.piday.org/.