Comment by jstanley
1 month ago
How do you make use of it? Is it basically logarithms of values? So add them together to multiply them? I don't know if I quite understand how the units would work.
As an example, "how long would it take for everyone in a large high school to microwave their meals if they all did it sequentially?".
People in a large high school is *4* (let's say about 3000 people).
Microwaving a meal is *2* (let's say 5 minutes).
So by Napkin Math we get 4+2=*6* which is a *large metropolitan area*.
Oops. I mean 11.6 days.
And with normal multiplication, 3000 * 5 = 10.4 days, so 11.6 days is a pretty good estimate.
So I think the answer is indeed "add the numbers together to multiply them", and be careful that you understand what units you're using.
Yeah, 'tool' here is a little generous. "list of order of magnitude of some things" is more like it
If notation is a tool of thought, seems reasonable to say a cheat sheet works as a tool too. It's like downloading more RAM for your brain.
>How do you make use of it?
It could be useful for Fermi estimation, where you generally only care about orders of magnitude.
https://en.wikipedia.org/wiki/Fermi_problem
How did you get 11.6?
Under the "Time (seconds)" section, I looked up "6", which is my result from 4+2:
> 6 11.6 days, two-week vacation, waiting for a passport, healing from minor surgery
11.6 days is what's listed for time 6, along with two-week vacation and some other examples.