Pi is a number that basically, never ends. The first five digits of Pi are "3.14159". Pi can be used to calculate the circumference of a circle, by either using the formula "Pi r squared" or "Pi x d". You can calculate the digits of Pi by using the formula "22 divided by 7".
There have been records of people memorizing Pi to over 67,000 digits. Several books devoted to Pi have been published in the past. There is also a whole day devoted to Pi called Pi day. The symbol of Pi is the same as the Greek letter Pi.
Wikipedia:Pi
Wikipedia: Supercomputers
Rhapsody on the proof of pi = 4: Correction: when I mark where pi is on the graph, I meant pi/2!
Note: If this video were supposed to be teaching you, I'd probably have to make it boring and say that in one sense of limits, spoiler alert, you actually do approach a circle and a line, solving the apparent paradox by saying that the invariant of length does not hold over infinity. Luckily I am an artist, and this is a Rhapsody, and instead of "learning," you get to actually think, if you like.