The average person knows maybe the first five or six digits of pi, trailing off somewhere around 3.141592, and even those who tout their superior memorization of the number probably only have about 20 digits to show off at the cocktail party. In other words, we know it’s lengthy, but have you ever stopped to really consider just how many digits make up this figure? It’s almost...irrational. (There's a little dad/math joke for your entertainment.)
The Leibniz Institute for Astrophysics Potsdam has a page with the first 5 million digits of pi, organized into nice little 50 digit cubes that march on for 500 pages. It’s staggering to scroll down and take in the sheer number of numbers, and also entertaining to plug in your phone number, birth date or other numerically significant sequence to see if you digits are written into a famed mathematical ratio.
Rajveer Meena holds the Guinness World Record for most pi decimal places memorized. He set the record earlier this year, and recited 70,000 digits while blindfolded. It took nearly 10 hours.
There's a ton of videos on YouTube with people showing their incredible memorization skills, like this one of middle school student Benjamin Most, who kept beating his own record at his school's annual pi recitation contest.