Comment by Mathnerd314

This seems more like Fermi estimation (https://en.wikipedia.org/wiki/Fermi_problem). And it is underrated and also it is really hard. I mean, it is easy for the author here to say "look I threw it into Google and it worked" but practically I have seen many people struggle with these sorts of problems - they get the wrong numbers, they divide instead of multiply, or whatever, and the units don't really help.