In astronomy, pi=1 or 10, depending on whether you’re trying to over or under estimate something. Because when you’re trying to estimate distances measured in millions of light years, the difference between 3 and 10 is just one or two orders of magnitude on a small number. It’s pretty common for astronomers to do napkin math by rounding every single number to the nearest zero. 91k becomes 100k for instance. Because the napkin math estimations are just trying to gauge whether some celestial event or object is a thousand light years away, ten thousand, a hundred thousand, etc… And pi becomes 10, because that’s the nearest round number.
Depends on the level of precision you need. If I want the volume in a 500 foot long, 3 inch pipe to roughly estimate how much supply I need to order, I wouldn’t need a calculator. It would very roughly be 90-95 ft3. (Divide 500 by 4 two times and multiple by 3)
Then I would spend 5 minutes double checking myself haha.
Even in engineering it is common to just round pi to 3 and quickly estimate whatever it is your doing.
In astronomy, pi=1 or 10, depending on whether you’re trying to over or under estimate something. Because when you’re trying to estimate distances measured in millions of light years, the difference between 3 and 10 is just one or two orders of magnitude on a small number. It’s pretty common for astronomers to do napkin math by rounding every single number to the nearest zero. 91k becomes 100k for instance. Because the napkin math estimations are just trying to gauge whether some celestial event or object is a thousand light years away, ten thousand, a hundred thousand, etc… And pi becomes 10, because that’s the nearest round number.
Fermi Estimation. Where you’re dealing with something so big, you’re just interested in the magnitude.
Excuse me what? I’ve been an engineer for a decade and have never met anyone that would do that. We have calculators.
I think they mean napkin math. Like you’re in a meeting and they ask for a general idea if something will work or not
I suppose. I’m still internally outraged and haven’t run into such a situation before, but I accept this.
To be fair most of the situations where I’ve run into this have never involved pi, and sometimes it’s just qualitative.
That makes sense. I feel like if you’re at the point where pi is meaningfully involved, you should probably do your math.
Yeah I agree. It isn’t that hard to set up things in Excel to get a decent answer.
We all have phones with calculators, don’t really need to do napkin math anymore
Depends on the level of precision you need. If I want the volume in a 500 foot long, 3 inch pipe to roughly estimate how much supply I need to order, I wouldn’t need a calculator. It would very roughly be 90-95 ft3. (Divide 500 by 4 two times and multiple by 3)
Then I would spend 5 minutes double checking myself haha.
I feel like a proper engineer would call only going two places past the decimal “rounding pie”.