this post was submitted on 09 Nov 2025
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[–] lauha@lemmy.world 162 points 3 days ago (2 children)

This is because fibonacci numbers approach golden ratio which is approximately 1,618033... and one mile is 1,609344 kilometres exactly.

[–] Oisteink@lemmy.world 28 points 3 days ago (1 children)
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[–] RememberTheApollo_@lemmy.world 9 points 2 days ago (2 children)

Interesting, but if I have to look up a conversion I’ll just look up the actual conversion rather than an approximation.

[–] Hufschmid@sopuli.xyz 8 points 2 days ago (1 children)

Why have brain when have computer

[–] pyre@lemmy.world 3 points 2 days ago

thanks to "AI" being in everything more and more computers are starting to perform worse than brain

[–] CompassRed@discuss.tchncs.de 2 points 2 days ago

The point is you don't have to look it up. Fibonacci is really easy to compute in your head.

[–] TheBat@lemmy.world 97 points 3 days ago* (last edited 3 days ago) (3 children)
[–] atro_city@fedia.io 40 points 3 days ago (4 children)

Nah, that's too difficult for USAians. They can memorize fibonacci numbers much more easily.

[–] WALLACE@feddit.uk 17 points 3 days ago (7 children)

Be like us Brits and measure short distances in metric, long distances in Imperial, yet struggle to convert between them.

GPS navigation gets frustrating. It's either metric "turn left in 4km" when all road signs and speeds are in miles, or imperial "turn in 200ft" when you have no idea how long 200ft is.

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[–] Aeao@lemmy.world 12 points 3 days ago (5 children)

Hey I’m going to have to ask you to censor that word. There’s American children on this ap! We can’t have them going to the playground and repeating that kind of language.

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[–] altkey@lemmy.dbzer0.com 8 points 3 days ago* (last edited 3 days ago)
H A T E S P E E C H
🚨🚨 A L E R T 🚨🚨
[–] Huschke@lemmy.world 8 points 2 days ago

I always used "a little more than half".

[–] Sir_Premiumhengst@lemmy.world 6 points 2 days ago

Works because ratio of km to miles is about the golden ratio.

[–] gnawmon@ttrpg.network 30 points 3 days ago (3 children)
[–] Landless2029@lemmy.world 13 points 3 days ago

And yet the military uses "clicks"

[–] PhAzE@lemmy.ca 14 points 3 days ago (7 children)

Just gotta ask any of the 90% of the world who use it to find out. Americans hate this one simple trick!

[–] gwl@lemmy.blahaj.zone 5 points 2 days ago* (last edited 2 days ago) (1 children)

Fun fact: there's quite a lot of countries that use "mixed metrics", with no real rhyme or reason for what uses old ancient imperial and what uses new shiny metric

UK - Miles for long distances, switch to meters for distances less than a mile, always use km in air and sea. Milk in pints, petrol in liters, water in ml, beer in pints. Human heights in Feet Inches, building heights in Meters. Human weights in a unit even Americans don't use anymore (Stone), animal weights in kg/g.

[–] zarkanian@sh.itjust.works 2 points 2 days ago* (last edited 2 days ago) (3 children)

Really? Do people walk around in the UK and say "I weigh 11 stone"? "I lost 3 stone on this diet"?

[–] cheesyxpickle@lemmy.ca 2 points 2 days ago (1 children)

Canadian here, I watch some UK fitness shows, can confirm.

[–] gwl@lemmy.blahaj.zone 1 points 1 day ago* (last edited 1 day ago)

Canada another that does the Mixed Metrics, but with entirely different sets of arbitrariness

[–] BeardedGingerWonder@feddit.uk 2 points 2 days ago

Yessir, stone and lbs usually.

So 12 stone 8 for example. 14lbs to the stone.

[–] gwl@lemmy.blahaj.zone 1 points 2 days ago

Yeah man, it's fucking nuts

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[–] gwl@lemmy.blahaj.zone 3 points 2 days ago

0.54 nmi (nautical miles)

[–] ExperimentalGuy@programming.dev 20 points 3 days ago (1 children)

This is such a cool example of how some recursive algorithms have a closed form. We all know that there's a simple equation to plug miles into to get kilometers, but we don't talk about how the Fibonacci sequence has a closed form. This is so cool.

[–] angrystego@lemmy.world 6 points 3 days ago (1 children)

Wjat does closed form mean? Asking as a stupid botanist, sorry.

[–] WolfLink@sh.itjust.works 5 points 2 days ago* (last edited 2 days ago)

Closed form means it can be written out as a specific, finite set of instructions that work the same regardless of what the input to your function is.

For Fibonacci, it is most commonly defined in its recursive form:

f(0) = 0
f(1) = 1
f(x) = f(x-1) + f(x-2) for integer x > 1

But using this form, computing a very large Fibonacci number requires computing all the numbers before it, so it’s not the same finite set of instructions for every number, it takes more computation to generate larger numbers.

However, there is a closed form formula for generating Fibonacci numbers. Using this formula, you can directly compute any large Fibonacci number without having to compute all those intermediate steps. It takes the same amount of work to compute any Fibonacci number.

f(x) = (a^x - b^x)/√5
a = (1+√5)/2
b = (1-√5)/2

(Note that a and b here are constants; I only wrote them separately to avoid a mess of nested parenthesis)

For an example of something that doesn’t have a closed form, we do not know of a closed form for generating prime numbers. There are several known algorithms for generating the nth prime number, but they all depend on computing all the previous prime numbers, making it very difficult to compute very large prime numbers (in fact, how generating large primes is actually done is by making an educated guess and then checking that it’s actually prime). Discovering a closed form formula for prime numbers would have a huge impact on mathematics and cryptography.

[–] Tollana1234567@lemmy.today 6 points 3 days ago (2 children)

isnt it easier to give them simple conversions 1mi=0.6km.

[–] SacralPlexus@lemmy.world 9 points 3 days ago (1 children)

Might want to check your units.

[–] gwl@lemmy.blahaj.zone 3 points 2 days ago* (last edited 2 days ago)

It's rough estimation, a deviation of anything less than 50% is accurate enough for that

Edit: Ooh I thought you were trying to "um actually, it's 1.66", but I just realised they put 0.6 instead of 1.6

[–] pupbiru@aussie.zone 5 points 3 days ago* (last edited 3 days ago)

or for in your head maths: half + 10%

(though it’s 1km=0.6mi, 1mi=1.6km)

[–] humanspiral@lemmy.ca 3 points 2 days ago

5 to 8 is the far simpler pretty exact conversion.

[–] ramble81@lemmy.zip 13 points 3 days ago (6 children)

To go from km to mi I always leaned “multiply by 6 and move the decimal one to the left”. So 6km is ~3.6mi. Or 10km is just about 6mi.

[–] davidagain@lemmy.world 7 points 3 days ago

Yes. That uses the 3:5 ratio.

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[–] gwl@lemmy.blahaj.zone 4 points 2 days ago* (last edited 2 days ago) (2 children)

Ah yes, I always remember the Fibonacci sequence and totally wouldn't find it harder to calculate than just doing the conversion the regular way

/sarcasm

[–] Gloomy@mander.xyz 5 points 2 days ago

But woudn't you only need the 3 = 5 part?

[–] Dumhuvud@programming.dev 4 points 2 days ago (2 children)

"Remember"? Do you also remember all the digits of π?

It's defined as F(0) = 0, F(1) = 1 and F(n) = F(n - 1) + F(n - 2). Which makes more sense than imperial units.

[–] gwl@lemmy.blahaj.zone 4 points 2 days ago* (last edited 2 days ago) (2 children)

Or I could just do 1.6 km ≈ 1 mile whenever I need to convert from the standard that I use, Metric, to Imperial

Far far far simpler

Edit: I'm not American, I use sensible units, SI Metric

Edit edit: I do fully have dyscalcus, mostly only effects "scary" looking maths, so no, your suggestion doesn't help

[–] Dumhuvud@programming.dev 1 points 1 day ago (1 children)

Tbh, the last sentence was just a silly jab at the imperial units.

I was mostly just making fun of the fact that you implied the Fibonacci sequence can be memorized, when it is infinite. I'm not saying that referring to it is simpler than dividing/multiplying by a constant, no.

[–] funkless_eck@sh.itjust.works 2 points 2 days ago (1 children)

I know from running that 5k is 3.1miles so I just go from there

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[–] UnderpantsWeevil@lemmy.world 1 points 2 days ago

Which makes more sense than imperial units.

But you'd only need to do the conversion if you started with imperial units.

[–] SkunkWorkz@lemmy.world 2 points 2 days ago (4 children)

I’m never going to visit the US or UK anyway.

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