system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 how do we use the pi symbol which represents an infinite number to find the area of a circle which is definite?

My friend posed this question to me and I had no intelligent response.

EDIT: okay! Pi isn't infinite!
gpt
Because Pi does not represent an infinite number! It's a fixed *ratio*, a fixed quantity, a little dot somewhere on the number-line between 3.1 and 3.2. It's a very very precise finite quantity - just as finite or definite as area and diameter.

It's only that calculating this quantity takes an infinite amount of steps. 


You have a wheel. The distance around the wheel is longer than the the diameter, right? How many times does the "diameter length" fit around the circle? You can cut a piece of string to a diameter, then curl it around the wheel and discover it goes around 3 times plus a bit extra. That bit extra is 1/10ths of the string...and a bit extra. *That* bit extra is 4/100ths of the string...and a bit extra etc. The string goes around exactly pi times, or 3.14159.. times. The string is always smaller than 3.2 - it doesn't have an infinite length!

It doesn't matter if your circle is smaller than an atom or bigger than a galaxy, the circumference is *always* 3.14159... times longer than the diameter. Diameter-to-Circumference is a fixed, finite, **ratio**.


Edit: corrected 3.1459... to 3.14159...!