arthur,

Do you remember the Fibonacci sequence? You can use it to convert miles to kilometers .

2 mi ~= 3km

5mi ~= 8km

8mi ~= 13km

13mi ~= 21km

And so on.

soggywhale,

That’s awesome thanks !

DoctorWhookah,

Wait, is this true until its not or is it true forever as you go higher in the sequence?

masochismworld,

Conversion factor of miles to kilometers is about 1.609 and golden ratio is about 1.618, it will be pretty accurate for quite a while…

liam_galt,
@liam_galt@lemmy.blahaj.zone avatar

It’s true forever. The Fibonacci sequence used in this way converges on the golden ratio, which is close to the conversion of km and mi.

Anticorp,

So are you telling me that the inventors of the mile were using the golden ratio?

Maya,

We wish they were that cool, the inventors of the modern mile were more concerned about land measurements. A square mile is 640 acres. Which neatly can be cut into quarters 3 times. 160, 40, 10.

arthur,

Just a neat coincidence

kakes,

Someone already replied with a graph, but I also got curious and checked for some higher numbers. Sure enough, it held up.

For example:
832,040mi => 1,346,269km (actual: 1,339,039km)

snek_boi, (edited )

I think the way to formally prove this is to find the difference between the Fibonacci approximation and the usual conversion, and then to find whether that series is convergent or not. Someone who has taken the appropriate pre-calculus or calculus course could actually carry it out :P

However, I got curious about graphing it for distances “small enough” like from Earth to the sun (150 million km). Turns out, there’s always an error, but the error doesn’t seem to be growing. In other words, except for the first few terms, the Fibonacci approximation works!

This graph grabs each “Fibonacci mile” and converts it to kilometers either with the usual conversion or the Fibonacci-approximation conversion. I also plotted a straight line to see if the points deviated.

https://lemmy.ml/pictrs/image/528b1166-8b5d-481d-a7bc-180947c29520.png

Edit: Here’s another graph

https://lemmy.ml/pictrs/image/003c6f1a-5555-45d3-a4d6-e4b5ddae71ec.png

So it turns out:

  • Fibonacci-approximated kilometers are always higher than the usual-conversion kilometers
  • At most, the difference between both is 25%. That happens early on in the terms.
  • After that, the percentage difference oscillates around a value and comes closer to it.
  • When talking about more than 100 miles, the percentage change approximates 0.54.

TL;DR:

  • Yes, the Fibonacci trick is true forever as you go higher in the sequence if you’re willing to accept a 0.54% error.
Akasazh,
@Akasazh@feddit.nl avatar

You just did the math!

snek_boi, (edited )

If someone wants to play around with the code, here it is.

Note that you need RStudio and the Tidyverse package.

klemptor,

Mmm dat ggplot2 but ggthemr::ggthemr(“flat”) is where it’s at.

snek_boi,

Checked it out and love that package! Thanks for the recommendation :)

kogasa,
@kogasa@programming.dev avatar

The ratio of consecutive terms of the Fibonacci sequence is approximately the golden ratio phi = ~1.618. This approximation gets more accurate as the sequence advances. One mile is ~1.609km. So technically for large enough numbers of miles, you will be off by about half a percent.

abejfehr,

It’s always true because the ratio of miles to km is really close to the golden ratio.

If you do it for a zillion miles you’ll be off by a lot of km, but proportionally the same amount as for 1 mile

newpuritan,
@newpuritan@lemmy.ml avatar

That’s brilliant.

danafest,

Simple recipe formulas that are scalable

HobbitFoot,

1 Stick of Butter 2 Egg Yolks 3 Tbsp of Lemon Juice

bigfish,

Baker’s ratios make my family think I’m a much better baker than I am.

Basic risen bread (a “60% hydration bread” ): 100 parts by weight of flour, 60-70 parts liquid, 3 parts salt, 2 parts yeast. Use grams and scale it up by 5 (500g flour), use water or beer for the liquid, knead, let rise for an hour or so, shape, rest for 30min, then bake at 400F for about an hour or until the inside is around 190-200F, and LET IT COOL to sub-120F before you cut in. Or if you’re feeling fancy, use scalded and cooled milk, add 5-10 parts sugar, and swap out 10-20 parts of the liquid for melted but not hot butter - and you get a nice rich bread, half way to a brioche. Or go to 70-75 parts liquid, including some olive oil, and kneed for a long time, and you got a solid pizza dough.

Quick breads: 2 parts flour, 2 parts liquid (including sugar), 1 part beaten egg, 1 part fat (oil or melted butter). This gives you a jumping if point for banana breads, pancakes, muffins, and scones. Add or withhold a little liquid to get the consistency you want for how you’re cooking it.

RustedSwitch,
@RustedSwitch@lemmy.world avatar

A crowd pleasing karaoke song!

whyrat,

I’ve never seen these flop at kareoke (if done with average competency):

Jump around - cypress hill gang

I will survive - Gloria Gaynor

Bohemian Rhapsody - Queen

Billy Jean - Michael Jackson (many other covers)

Shake it off - Taylor Swift

Pick 1 of the above plus a Beatles song and you’re good for impromptu Kareoke.

If you have a few days notice and a friend to plan with the options expand…

checkymander,

I tried Bohemian Rhapsody once at karaoke, realized quick that I did not have the range for that song.

pruwybn,
@pruwybn@discuss.tchncs.de avatar

Yeah, that one definitely flopped when I tried it.

HobbitFoot,

New Jersey state law requires everyone to sing along to Don’t Stop Believing.

RustedSwitch,
@RustedSwitch@lemmy.world avatar

I’ve got Sir Mixalot’s “I like big butts” on lock

qjkxbmwvz,

Given that you cannot lie, this must be true.

klemptor,

I once chose Paradise By The Dashboard Light for karaoke and that was the only time I’ve ever done karaoke because I’m still embarrassed ten years later at how awful a choice it was. Great song, terrible for karaoke.

confetti_8tVST5,
  • Useful: Times tables/math formulas if you havent already.
  • Fun: the way to solve a rubik’s cube so you can show off
ProvokedGamer,
@ProvokedGamer@lemmy.ml avatar

For the rubix cube one, besides showing off, it’s also fun to learn how to solve it and practicing to get faster and faster at solving it. It’s worth it.

MammyWhammy,

I got down to about a minute and then realized it would take a lot more time to get lower than that.

Pulptastic,

My problem is everything makes sense until the last face. The algorithms seem too abstract at that point; it is memorizing a thing vs intuiting a thing.

sequential,

countries and facts about countries!

Ultraviolet,

The Doomsday rule.

Not necessarily the part for calculating the day of the week for any arbitrary day centuries ago, that’s just a useless party trick, but for the current year so you don’t need to pull out your phone to check. Knowing that 1/3 (or 1/4 on a leap year), the last day of February, 3/14, 4/4, 5/9, 6/6, 7/11, 8/8, 9/5, 10/10, 11/7, and 12/12 are all the same day of the week, that this year they’re all Tuesdays, and next year they’re all Thursdays, is mostly easy to remember and very frequently useful.

feral_hedgehog,
@feral_hedgehog@pawb.social avatar

Powers of two, squares and cubes up to 20 and the NATO phonetic alphabet.

ohlaph,

Harlow is in the fireplace, Adobo is in the window, and Sesqua is on the couch.

For some reason, I used the memory palace to remember that several years ago when I first heard about it and I still remember it.

abbadon420,

What does it mean?

ohlaph,

Pure randomness. Just wanted to try and memorize random things to see if it works.

hsl,
@hsl@wayfarershaven.eu avatar

Thirty days has September, April, June, and November.

frogfruit,

My school taught it as “30 days hath September, April, June, and November. All the rest have 31, except the second month alone.”

Notyou,

I always just used the knuckle trick for counting. The ones that have 31 days are at the top of the knuckle and the 30 (or 28/9) day months are in between the knuckles.

Deelala0516,

This is definitely the way.

penguin_in_suit,

With 28 there is only one All the other are thirty one

My mom taught me this limerick when I was little.

torknorggren,

Baseball-reference.com

Zarxrax,

Learn some alphabets of foreign languages. Russian is fun because some of the characters looks like English letters but have completely different sounds. Korean is also cool because it looks crazy complex but it’s actually extremely simple.

MammyWhammy,

I don’t know any Korean, but the Korean alphabet is by far the best writing system I’ve seen.

The characters make the shape your mouth makes while annunciating that letter. It’s ingenious.

bitcrafter,

For day-to-day purposes, if you are used to Fahrenheit but not Celsius or vice versa, and all you want to do is get a rough sense of how warm or cold it is outside without having to do arithmetic involving fractions in your head, then remember that there are two temperatures in Celsius that are roughly the same in Fahrenheit but with their digits transposed: 16° C ~ 61° F, and 28° C ~ 82° F. You can then roughly interpolate/extrapolate by about 2° F for every 1° C.

Anticorp,

Also freezing is 0 in Celsius, so 32f is 0c. That one always helps me. Not as useful for converting c to f.

Climinteedus,

Alternatively, 100C is boiling, which is 212F.

venusenvy47,

Bob and Doug Mackenzie thought me to roughly convert C to F by taking the temperature in Celsius, doubling it and then adding 30. It gets you in the ballpark.

csolisr, (edited )

Converting Celsius to Fahrenheit:

  • multiply by 2
  • remove 10%
  • add 32
baconeater,

This is wrong? Taking 20°C as an example. Following this formula gives 48°F when it should be 68. Could you perhaps be supposed to add 32 instead of 12?

ips,
@ips@infosec.pub avatar

Adding 32 is correct.

linearchaos,
@linearchaos@lemmy.world avatar

Yeah, it’s supposed to be c * 2 + 30

Today,

Thats a very close approximate and what i use when it’s numbers i have to think about for 5/9 and 9/5.

ips,
@ips@infosec.pub avatar

f = c * (9/5) + 32

linearchaos,
@linearchaos@lemmy.world avatar

I mean you’re not wrong Walter.

The concept is that it’s a formula you can do in your head most people aren’t going to spend a minute trying to work out 9/5 in their head

PhreakyByNature,

I mean… That’s just like… Your opinion man.

linearchaos,
@linearchaos@lemmy.world avatar

Whoever downvoted your comment is a nihilist

PhreakyByNature,

They’re out of their element.

linearchaos,
@linearchaos@lemmy.world avatar

That comment REALLY tied the thread together, Did It Not?

PhreakyByNature,

It really did Dude.

Candelestine,

Nothing can go faster than the speed of light, not even fahrenheit temperature units.

linearchaos,
@linearchaos@lemmy.world avatar

Nah, the speed of light in air is faster than the speed of light in peanut butter.

kafa,

yes, but that’s speed of light

¯⁠⁠_⁠(⁠ツ⁠)⁠_⁠/⁠¯

csolisr,

Thanks for noticing the typo

rm_dash_r_star,
@rm_dash_r_star@lemm.ee avatar

I have this thing about astronomy. Kind of a perspective thing of our place in the cosmos. I try to remember all the distances of planets from the sun and distances of moons from their planets. Also the diameters of solar objects. There’s other factoids I try to remember about neighboring solar systems and galactic bodies. For example I remember the black hole at the center our galaxy is called Sagitarius A and its mass is 4M suns. The black hole at the center Andromeda our closest major galaxy at 2.5M light years is 25M suns. The black hole at the center M87, the closest active galaxy at 50M light years is 4B suns. I didn’t look that stuff up so tell me if I didn’t get it right.

Chrobin,

Correction: It’s Sagittarius A*

tinwhiskers,
@tinwhiskers@kbin.social avatar

Anyone who isn't at least mildly interested that you know Morse code isn't someone you want to know :-)

Good filter technique.

snek_boi,

what if someone is mildly interested in why you use it as a filter technique? :P

state_electrician,

Also works the other way around, which is neat.

the_inebriati,

In that you know to avoid the weirdo in the corner wearing a “Ask me why I know morse code” t-shirt at the party?

state_electrician,

Correct.

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