system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How are new digits of Pi discovered?
gpt
There are some infinite series that equal π.  The most well-known is

> π = 4 * (1 - 1/3 + 1/5 - 1/7 + 1/9 ± ...)

Computers calculate an arbitrary number of digits of π by just calculating more and more terms and adding them up.  In practice, they don't use the series above, they use a more complicated one that converges more quickly, but the principle is the same.