| url = http://www-groups.dcs.st-and.ac.uk/history/HistTopics/Pi_through_the_ages.html
| title = A history or Pi
| accessdate = 2012-02-11}}</ref> who selected '''<big><math>\pi</math></big>''' because it is the first letter of the [[Greek]] word for [[perimeter]] (''περίμετρος''), ''i.e.'', the circumference of a circle is its perimeter. A [[Swiss]] mathematician, [[Leonhard Euler]], then popularized the notation in 1737 as he did for other symbols.<ref>https://www.historytoday.com/archive/feature/man-who-invented-pi</ref> The [[infinite]] length of ostensibly [[random]] decimal points in <math>\pi</math> lead to the assumption that pi is a [[normal number]](which is demonstrated by computer calculations of <math>\pi</math> to trillions of digits): it contains every possible finite sequence of digits, and therefore, every birthday, even the equivalent of every book ever written. Simply stated, '''''[[Essay:pi contains pi|Pi contains pi]]''''', beginning an infinite number of digits into it (which avoids the periodicity problem).
<big><math>\pi</math></big> is referenced in the [[Bible]], literature, and even as the title of a movie. It is central to the most famous identity in all of mathematics: [[Euler's Formula|Euler's Identity]].