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c/xkcd · by schnurrito@discuss.tchncs.de · 1y

xkcd #3023: The Maritime Approximation

https://xkcd.com/3023/

It works because a nautical mile is based on a degree of latitude, and the Earth (e) is a circle.

https://explainxkcd.com/3023/

146 points · 9 comments · view on lemmy.world

9 Comments

palordrolap@fedia.io · 35 pts · 1y (4 replies)

Obligatory repeat of the fact that the ratio between miles and kilometres is ln(5), correct to less than 0.01% (yes, that's a percent of a percent).

The golden ratio or Fibonacci numbers are used more often for the same trick but they're off by, at best, very slightly worse than 0.5%.

agamemnonymous@sh.itjust.works · 7 pts · 1y (1 reply)

Fibonacci numbers are easier than ln(5) to calculate on the spot tho

palordrolap@fedia.io · 2 pts · 1y

You're not wrong. The ln(5) trick is for when you have a scientific calculator but it doesn't have the conversion built in.

matj1@lemmy.world · 2 pts · 1y (1 reply)

correct to less than %%

palordrolap@fedia.io · 3 pts · 1y

‱

matj1@lemmy.world · 10 pts · 1y

Knot is just nautical mile per hour, so it can be simplified so:

π miles = e nautical miles

rockerface@lemm.ee · 8 pts · 1y

Thanks, I hate it

marcos@lemmy.world · 2 pts · 1y

This is cursed on so many different levels!

captain_aggravated@sh.itjust.works · 1 pts · 1y

God french fry filching dammit.