Egyptian Fractions and the Greedy Algorithm - Numberphile

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2 июн 2024

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Комментарии : 313

@numberphile 5 месяцев назад

See brilliant.org/numberphile for Brilliant and 20% off their premium service & 30-day trial (episode sponsor)

@tomasruzicka9835 5 месяцев назад

1'000'000 == MAX_EGYPTIAN_INT 😂😂😂

@swirlingabyss 5 месяцев назад

Whoever created that "bent finger" heiroglyph was a different kind of numberphile.

@michaelrockwell9691 5 месяцев назад

Yeah, he was definitely counting to 11.

@jamesedwards6173 4 месяца назад

@@michaelrockwell9691 🤣

@mobilephil244 3 месяца назад

It was probably a Microsoft help desk employee

@aryst0krat 5 месяцев назад

Poor Sophie ahaha. "It's a finger. A *finger.*"

@NothingYouknow96 5 месяцев назад

I respectfully disagree

@bholdr----0 5 месяцев назад

Yeah that's what I thought. I mean, 'finger' wouldn't be my first guess at what that is supposed to represent... lol.

@dielaughing73 5 месяцев назад

Sure it is

@brainboy7123 5 месяцев назад

Maybe it is supposed to be a bent finger but from head on.

@proloycodes 5 месяцев назад

look up the actual symbols, they actually look like a bent finger.

@syedmoheelraza4161 5 месяцев назад

Sounds like a promising way to calculate the value of 1 to any number of decimal places!

@vigilantcosmicpenguin8721 5 месяцев назад

Not to brag, but I have the value of 1 memorized to over 100 decimal places.

@theblinkingbrownie4654 4 месяца назад

@@vigilantcosmicpenguin8721I've only memorized the first 60, keep up the grind 💪

@rosiefay7283 5 месяцев назад

I think credit should be given to the mathematician who devised the greedy algorithm and proved that it terminates. He was Leonardo of Pisa, better known as Fibonacci.

@Felipe-sw8wp 5 месяцев назад

Fibonacci strikes again. But jokes aside now, could you give more on this? When did he use it?

@wesleydeng71 5 месяцев назад

@@Felipe-sw8wp Greedy algorithm was developed by Fibonacci, not the Egyptians who did not use it.

@KenFullman 5 месяцев назад

Which proves that the ancient Egyptians had time travel. Which is why they could use the greedy algorythm centuries before the birth of Leonardo.

@bobSeigar 5 месяцев назад

@@KenFullmanFalse equivalency. 'Akkadians drew circles, therefore Pi.'

@KenFullman 5 месяцев назад

@@bobSeigarAkkadians lived in Mess of Potatmia and they drew triangles, which is why we still call the longest side of a triangle the hippopotamus.

@thananightshade 5 месяцев назад

This makes PERFECT sense when you think about how this would be used in everyday life. If my taxes from a days milling is 11/12 of a bushel (or proper historic unit) I am going to use 1/n sized scoops to measure out my payment. So 11/12 would be 1 - 1/3 of a 1/4 measure, if the smallest measuring tool I had was a 1/4 (unit) bowl.

@krisrhodes5180 5 месяцев назад

I was thinking the practicality comes from the fact that this system means you don't have to have multiple copies of all your fractional measurement things (weights, containers) and can instead do whatever you need with just one of each. Instead of having to measure 7/9 by having seven 1/9th weights, I can do it with the single 1/2, 1/4 and 1/18 weights I already have. (And I can just add precision as needed by buying a new weight just one denominator larger than what I already have.)

@thischannelhasnocontent8629 5 месяцев назад

The other practical component is it makes dividing things among people easier. Say you need to divide 5 pizzas among 8 people. 5/8 is 1/2 + 1/8, so each person can get half of a pizza plus an eighth, rather than having to divide the pizza into 40 slices and give everyone 5.

@rosiefay7283 5 месяцев назад

The greedy algorithm is a mathematician's algorithm rather than a really practical one. It does terminate but it might use more fractions than the minimum that are enough. And its priority of greed over exploiting factors of the starting fraction's denominator sometimes leads it to overlook simple solutions. The simplest fraction where it is not best is 4/17. The greedy algorithm uses four denoms: 5, 29, 1233, 3039345. But three denoms are enough: 5, 5*6, 5*6*17. One where it overlooks a factor in the starting denom: 4/49. The greedy algorithm uses four denoms: 13, 213, 67841, 9204734721. But two denoms are enough: 14, 98 [edit: typo corrected].

@Felipe-sw8wp 5 месяцев назад

Very nice. Any hint on how you got those better fractions? Just one thing, I believe there is a mistake on the last example, because 1/7 is bigger than 4/49 so it can't be that 4/49=1/7+1/98. (I've checked the others, they all work).

@columbus8myhw 5 месяцев назад

@@Felipe-sw8wp I think it should be 14, 98. That is, 4/49 = 1/14 + 1/98.

@minamagdy4126 5 месяцев назад

Fun fact, the ancient Egyptian thought so too. In fact, deciphering how they got near-minimal representations (and what they considered minimal in the first place) is a whole area of study in and of itself. I remember doing a research paper for a course about this, and some of the sources have very interesting theories.

@papalyosha 5 месяцев назад

Nice examples. (But the last one has a typo: 4/49 = 1/14 + 1/98). BTW, Egyptians did not use greedy algorithm. E.g. in Ahmes Papyrus 2/49=1/28+1/196. The greedy algorithm would gave: 1/25+1/1225. Ahmes' answer is much nicer. And it follows immediately from it that 4/49 = 1/14+1/98. So Egyptians were more efficient than the greedy algorithm.

@randomname285 5 месяцев назад

@@papalyosha was wondering why the greedy algorithm wouldn't pick up 1/7, but of course 1/7 is less than 4/49, so should have twigged

@KYZ__1 5 месяцев назад

The scribe of the Rhind Papyrus, Ahmes, opened this historic works of 84 various problems by asserting he would study 'the knowledge of all secrets'. I prefer to refer to it as the Ahmes Papyrus in honour of its writer! (Henry Rhind was the 19th century buyer of the papyrus.)

@charlytaylor1748 5 месяцев назад

nice input

@Rubrickety 5 месяцев назад

Sometimes a bent finger is just a bent finger.

@KYZ__1 5 месяцев назад

The Ancient Egyptians felt particularly comfortable with the fraction 2/3. One reason for this that is linked to their desire to express fractions that would be irreducible to us today as the sum of many unit fractions: because 2/3 of any unit fraction 1/n = 1/2n + 1/6n. As a result, even to find 1/3 of a number the Ancient Egyptians would first find 2/3 of it and then halve the result!

@proloycodes 5 месяцев назад

isn't 1/2n+1/6n=8n/12n^2=2/3n?

@KYZ__1 5 месяцев назад

@@proloycodes Sorry, my bad, I meant to say that 2/3 of 1/n = 1/2n + 1/6n. Well spotted. Corrected it now

@landsgevaer 5 месяцев назад

I don't get it: since ⅔=½+⅙, it *isn't* irreducible to unit fractions, right?

@proloycodes 5 месяцев назад

@@landsgevaer it is irreducible to us because there are no common factors of 2 & 3 (except 1). it is reducible to sums of unit fractions though

@Mnaughten601 5 месяцев назад

@@landsgevaer how do you do the fractions in your reply? Is it a LaTex filter? Natural command?

@sk8rdman 5 месяцев назад

This felt like it ended abruptly. Though I guess no discussion about ancient number systems could be complete with a single RU-vid video; especially one less than 10 minutes long.

@canalsoundtest 5 месяцев назад

So in all of a sudden we came to know the origin of Super Mario's Piranha Plant

@kray3883 5 месяцев назад

Yes, yes, yes! That is 1000% (see what I did there?) a piranha plant!

@Mnaughten601 5 месяцев назад

Egyptian fractions was one of my research projects for my final semester. Also my favorite project.

@RussellBeattie 5 месяцев назад

3:43 The exact moment I got _totally_ lost.

@de_oScar 2 месяца назад

Maybe en example will help you. For any [positive] proper fraction with numerator different than 1 (denoted as p/q), there are fractions like 1/something, which are less than this, and we are searching for the biggest of them (so for 3/5 it would be 1/2; 1/3 is smaller than 3/5, too, but 1/2 is the biggest fraction with numerator 1 that is less 3/5, so we choose that one). "Greedy algorithm" means that for whatever is left we repeat this process, so after subtracting 1/2 from 3/5, we are left with 1/10. In this example we are done - the egyptian fraction for 3/5 is: 1/2 + 1/10. (Egyptian fraction for any p/q is 1/a+ 1/b + 1/c + … and so on.) I hope that helps somewhat.

@evilotis01 5 месяцев назад

thiis is facinating, bc constructing these numbers in the denominator is reminiscent of how every number can be constructed from prime factors, except in this case it's with addition rather than multiplication

@MegaKotai 5 месяцев назад

4:42 You don't substitute, you just rearrange the inequality.

@Kwprules 5 месяцев назад

Oh thank goodness… I spent minutes trying to figure out what substituted for what until I decided to check the comments. Thanks!

@KatScratchFever123 5 месяцев назад

Me, too!! Thank you for clarifying!

@enriquekahn9405 5 месяцев назад

I learned about Egyptian fractions from David Reimer's book "Count like an Egyptian." Highly recommend.

@Mikey_AK_12 5 месяцев назад

I studied this in my history of math course and didn't remember the conclusion, whether or not every rational number was possible. I was thinking about this question this week and this video showed up to answer it! Excellent timing!

@bholdr----0 5 месяцев назад

Kinda like the 'very large number represents infinity', in a biblical context '40' tends to mean 'quite a while', or 'a significant amount of time', rather than literally 40 years wandering, 40 days and nights of rain, etc. I find that (and the million=infinity) really interesting and perhaps revealing about the culture/context/etc... any other examples?

@lonestarr1490 5 месяцев назад

Yes. It's basically the same in Japanese and, I think, Chinese, where their respective word for 10.000 can also mean "an inconceivable shitload of".

@dAvrilthebear 5 месяцев назад

In old Russian 10.000 apparently played that part, and the name for 10 000 -- "t'ma", that literally translates as "darkness", is now used to mean "uncountably many (people)" .😊

@EebstertheGreat 5 месяцев назад

@@lonestarr1490 Also Greek. "Myriad" literally means 10,000, but traditionally it could also just mean "a great number," which it still means today in English.

@FLPhotoCatcher 5 месяцев назад

That's just a conjecture by non-Christians. The bible contains *many* larger numbers, and some *much larger* numbers, the largest being two hundred million ("twice ten thousand times ten thousand"). One hundred million ("ten thousand times ten thousand") is also written.

@FinnMcRiangabra 5 месяцев назад

Is there any extra-biblical support that '40' means 'quite a while'?

@davidgillies620 5 месяцев назад

You can split a unit fraction into two unit fractions by the substitution 1/n -> 1/(n + 1) + 1/(n^2 + n). So for example 1/26 = 1/27 + 1/702.

@NickEllis-nr6ot 5 месяцев назад

Enjoy Sophie's energy and explanations!

@FedeDragon_ 5 месяцев назад

and handwriting!

@Ric4562 5 месяцев назад

And the accent

@FloppaTheBased 5 месяцев назад

halo effect from looks lol

@queueeeee9000 5 месяцев назад

Sophie is my absolute favorite ❤

@fugoogle_was_already_taken 5 месяцев назад

This is one of the wierdest pen holding style I've ever seen :DD

@smurfyday 2 месяца назад

You ain't seen nothing

@blue_tetris 5 месяцев назад

I do wonder what need the ancient Egyptians had for counting a million things. It's clear they were doing some big-numbers arithmetic at that point. They knew they had a thousand of a thing that was also thousand.

@evilotis01 5 месяцев назад

it's a fair question, but at the same time, they were humans, and there's a very human desire to be like, well, what's bigger than a thousand? the overwhelming majority of us have no need for the numbers generated by tetration, pentation, etc, but we do it anyway because big numbers are kind of awesome

@Kaepsele337 5 месяцев назад

The pyramids contain more than a million stones for example. However, an empire like Egypt also needs numbers in that range to handle food distribution and administration in general.

@mwffu2b 5 месяцев назад

I mean...The Great Pyramid consists of an estimated 2.3 million blocks...

@robmarney 5 месяцев назад

Accounting. The Narmer Macehead records a total plunder of 1,422,000 goats, 400,000 cattle, and 120,000 human captives.

@ColonDee. 5 месяцев назад

They needed a way to count the money aliens paid them for building the pyramids

@HeHasNoName 5 месяцев назад

I think I say this every time, but Sophie has the neatest writing ive ever seen lol

@koopermeier7480 5 месяцев назад

Strange that the symbol for 1/2 looks like the graph of y=x^1/2

@BobStein 5 месяцев назад

Someone invented Egyptian Fractions to avoid getting on the pyramid crew.

@SgtSupaman 5 месяцев назад

It's pretty similar to writing decimal numbers in binary. .1 = 1/2 .01 = 1/4 etc. So to get 1/3, you need 1/4 + 1/16 + 1/64 + ... and you have .010101...

@randomxnp 5 месяцев назад

That's not a water lily. That is Audrey the man-eating plant from Little Shop of Horrors.

@ubk42 5 месяцев назад

There are cases where there is more than one way to give an Egyptian fraction. Did they prefer one over another in that case, for example the one coming from the greedy algorithm?

@PhotonBeast 5 месяцев назад

I can only imagine ancient Egyptians using 10 10000 10 as a meme joke. :)

@tomholroyd7519 5 месяцев назад

Yeah, like that thing hanging off Orion's Belt. That's not a sword. It's over 9000!!

@anders630 5 месяцев назад

So was egyptian maths and numbers more practical than roman or did they use similar ideas with fractions with just different representation for numbers?

@glenm99 5 месяцев назад

My understanding is that the Roman system is a distant descendant of the Egyptian system(s), with various improvements/adaptations made along the way. For example, the subtractive elements of the Roman system make calculation using an abacus or reckoning board faster (in some circumstances). Roman fractions are base 12, which in one way is very awkward, but in another way is very convenient. It's funny that today, we still have that same argument regarding metric versus imperial measurement.

@alanhersch4617 5 месяцев назад

@@glenm99 Yup that is the ONE big advantage of imperial IMO, is that fractions are easier in base 12. I used to work construction and can confirm it DOES make mental math easier. Now when used for larger measurements likes miles........ yeah that is where it gets silly.

@seannee3896 5 месяцев назад

Interesting! I wonder if this relates to Eudoxus theory of proprtions.

@bholdr----0 5 месяцев назад

40 years wandering, etc? 40 usually meant 'quite a while', or, 'a long dang time', rather than exactly 40 of whatever. Cheers

@EconAtheist 27 дней назад

[me @0:49]: "... Pac-Man exploding out of a hemispherical cake"

@hhh-ul2uu 5 месяцев назад

I remember you from watford girls! Cool to see you on here!

@jpdemer5 5 месяцев назад

2, 3, 7, 43, 1807 ... gets very large very quickly. It's known as Sylvester's sequence (OEIS A000058).

@Misteribel 5 месяцев назад

Can we pause for a second and be in awe of the fact we're watching a mathematician flawlessly writing hieroglyphs, and in such clear handwriting? ❤

@Starlight51739 5 месяцев назад

Yes we can ❤

@chriscraven9572 5 месяцев назад

I'd love to see the papyrus with pi written down.

@ask_os_2229 5 месяцев назад

That’s a bent finger alright! It resembles nothing else that I can think of.

@jamesroseii 5 месяцев назад

Ah, yes... Ancient Egyptian Algebra. I had a nightmare about this once...I think I was in my underwear...

@filpaul 5 месяцев назад

I'll never get back to sleep… _snore_

@mr.mentat.0x 5 месяцев назад

Your handwriting is quite beautiful. Explained really well too! 😊

@Furiac. 5 месяцев назад

Accidentally clicked on this video and i dont regret it

@dontich 5 месяцев назад

My 4 year old has the same concept for 100. Anything that is a ton of something is simply 100- id assume it’s the same idea for Egyptian 1M

@juanausensi499 3 месяца назад

It's still somewhat used in today's English. The word 'miriad' has two meanings, one is 10,000, the other one is 'too many to count'.

@MooImABunny 5 месяцев назад

when you calculated the egyptian fraction for 1, it got me thinking. you get 1/2, 1/2+1/3=5/6, 5/6+1/7=41/42 If you get to a fraction of the form (a-1)/a, then the next fraction you can add is 1/(a+1). (a-1)/a + 1/(a+1) = [(a-1)(a+1) + a]/a(a+1) = [(a-1)(a+1) + (a+1) - 1]/a(a+1) = [a(a+1) - 1]/a(a+1) so you again get a fraction of the form (a'-1)/a', with a' = a(a+1) so to compute this series, you just need to compute the sequence a[n+1] = a[n](a[n] + 1), a[0] = 2 which grows pretty fast, faster than 2^(2^n), which is pretty damn fast 2, 6, 42, 1806, 3263442,...

@colonialgandalf 5 месяцев назад

"Groundbraking. Its called.. A single stroke." (Chefs kiss for us simple-minded folks.)

@n0tthemessiah 5 месяцев назад

The number 1 and a single tally mark -- name a more iconic duo

@emanuelecerri8806 5 месяцев назад

And what about using continued fractions to obtain the" 1/n"s?

@johnacetable7201 4 месяца назад

2:55 my best guess is one word. Efficiency.

@pierreabbat6157 5 месяцев назад

When not writing in Egyptian, I use the notation R, both for "reciprocal" and for the Egyptian letter. So R2R3R6R43. Does Tweety Bird know the Sylvester sequence?

@minamagdy4126 5 месяцев назад

Modern academic literature uses over-lining, which is nearly the same as how ancient Egyptians did in Hieratic (their preferred non-fancy script that is just as old as Hieroglyphics), so you're not far off.

@CheshireTomcat68 5 месяцев назад

New wave of Numberphile Mathematicians.

@nickotrondou7481 5 месяцев назад

“that’s a bent finger”

@NothingYouknow96 5 месяцев назад

I hardly see it

@WilliametcCook 5 месяцев назад

7:43 Would you be able to use this to approximate irrational numbers?

@danielyuan9862 5 месяцев назад

I think so, but idk how practical that is.

@s00s77 5 месяцев назад

8:00 what about 1/2+1/3+1/6=1?

@minamagdy4126 5 месяцев назад

That exactly equals one. The expressions in questions are meant to be minimally less than one

@tauIrrydah 3 месяца назад

It is backwards, but it depends which direction you're writing, because hieroglphyics are read in either direction.

@ahmadnicole3744 5 месяцев назад

I have a conjecture that the rational number p/q will terminate in at most [2^(n-1)

@SanneBerkhuizen 5 месяцев назад

Is it just me, or are mathematicians getting cooler? Doctor Crawford, this amazing person. Even Parker is looking way Cooler than a few years ago. Is there a coolness - time diagram for mathematicians?

@d4slaimless 5 месяцев назад

This is interesting way to hold a pen. Very uncomfortable even to look at.

@sdr9682 5 месяцев назад

So, the Egyptians could express numbers in the millions. And Roman numerals only go to Thousands

@skyscraperfan 5 месяцев назад

There is a conjecture that if the denominator is 4, the process will stop after four steps or earlier. So I wonder what happens for other denominators.

@lonestarr1490 5 месяцев назад

A conjecture you say? I'd say that's completely obvious... Or am I off the rails here? Which denominator do you mean?

@skyscraperfan 5 месяцев назад

@@lonestarr1490 I looked it up. The conjecture is that for n>2 4/n=1/a+1/b+1/c for some integers a,b,c. So it you do no even need the d. It is called "Erdos-Strauss-Conjecture". Of course, if you allow four summands, it would be trivial. Obviously 4/n=1/n+1/n+1/n+1/n. That was my mistake. With only three summands it is not trivial though. For any n you will find a,b,c that make it work, but it has not been proven for every n. If you can prove it, you will become famous in the maths world.

@lonestarr1490 5 месяцев назад

Ah, not the denominator, but the numerator! Yes, that's another beast completely.

@skyscraperfan 5 месяцев назад

@@lonestarr1490 Haha, I always mix those up, as I know them as dividend and divisor in German. The problem looks so simple, but people have probably spent years on trying to solve it. I wonder if there is a simple solution that nobody has thought of yet.

@lonestarr1490 5 месяцев назад

@@skyscraperfan I also checked trice if I have them the right way around ;) That's usually the gist in number theory: the problems always appear to be trivial and you wonder if there's a clever and short solution nobody thought of thus far. And in fact, there are problems where this was the case. But they're the exception. Usually, number theory problems are freaking hard. That's especially true for every conjecture that comes with the name of Paul Erdös attached ;)

@reportedstolen3603 5 месяцев назад

Ahh the teachers of the Greeks. I love the history of mathematics

@testdasi 5 месяцев назад

01:00 - No amount of persuasion will tell me that's a bent finger. In fact I'm worried this vid will be demonitised. 😂😂😂

@jschoete3430 5 месяцев назад

What am I missing here? Of course there's always a way to write any fraction as a sum of fractions with 1 in the numerator: p/q = 1/q + 1/q + ... + 1/q, and this p times? Is this video rather a statement that it works as well when greedily writing the fraction down? Also why is 1/2 + 1/3 + 1/7 the Egyptian fraction closest to one when we clearly have 1/2 + 1/3 + 1/6 which is closer? Or is the latter not an Egyptian fraction? This video was going a bit too fast... EDIT: Oh, an Egyptian fraction has all different denominators as stated in the video. I suppose this means Egyptian fractions can only be constructed in this greedy manner for fractions less than one, since otherwise one would have lots of 1/1 + 1/1 + ... until getting to the decimal part.

@aioia3885 5 месяцев назад

i don't know the details but I'm pretty sure the Egyptians were not interested on repeating the same fraction more than once for some reason. maybe because 1/7 + 1/7 + 1/7 + 1/7 + 1/7 + 1/7 is way longer than 1/2 + 1/3 + 1/42? or how 20/21 is just 1/2+1/3+1/9+1/126 also I would assume 1/2+1/3+1/7 is the closest to 1 without actually being equal to 1

@holgerchristiansen4003 5 месяцев назад

Yes, you are overlooking something: All denominators in egyptian fractions have to be distinct. So 1/q+1/q wouldn't work for their system. As or the other thing: 1/1 is technically a fraction as well, so I suppose the "without being equal to 1" aioia mentioned is needed here.

@jschoete3430 5 месяцев назад

@@aioia3885 oh yes the "closest without equaling" was missing in the video, thanks!

@minamagdy4126 5 месяцев назад

Ancient Egyptians were perfectly fine concatenating regular and reciprocal numbers in a form of addition, similar to concatenating digits to build up the number's size and (right of the decimal point) precision amount. They also had tables for how to double odd reciprocals to aid with preserving the unique-denominator property for the result of general addition and multiplication.

@DaTux91 5 месяцев назад

We all know that's not a bent finger... It's a lit candle! 🕯️

@petrospaulos7736 5 месяцев назад

for anyone wondering 2, 3, 7, 43.... is a(n+1) = a(n)^2 - a(n) + 1, with a(0) = 2

@_Rizzics 5 месяцев назад

Woah, hold up, what's that in the thumbnail?💀

@1.4142 5 месяцев назад

bent finger

@johnchessant3012 5 месяцев назад

Sylvester's sequence

@Qermaq 5 месяцев назад

Making fractions with the Greedo algorithm - Han shot first.

@frankkrar 5 месяцев назад

That bent finger though...

@sammarks9146 5 месяцев назад

"You want a million of them? ... Heh!"

@bornfromstardust1526 5 месяцев назад

That Thumbnail.😮

@danyael777 5 месяцев назад

Today: _One Million_ Ancient Egyptians: _Soooo much!_ \o/

@arekwittbrodt 5 месяцев назад

Ancient Egyptians had very nice symbol for ten. Personally I would use it in the dozenal system instead of X, but alas! - there is already some kind of tradition in this regard. ;-) P.S. Had any ancient civilization, by chance, a symbol for eleven?

@markhubbart8903 5 месяцев назад

Interesting question, I didn't find any that have a single written symbol for 11. Even in those languages that don't use base 10 numbering system generally break the words and symbols down to a "ten and" style. One I found that doesn't is the Huli language, spoken in Papua New Guinea, which uses a base 15 counting system, with unique words for 1-15. No written symbols that I could find, though. Thanks for the rabbit hole, it was fun.

@arekwittbrodt 5 месяцев назад

@@markhubbart8903 You're welcome ;-) And thank you for finding the Huli counting system. I didn't know about it despite Wikipedia mentioning it ;-)

@ErikLeonardWagner 5 месяцев назад

"i looked into it! dont really know what that does!" hilarious

@maxeuker2949 5 месяцев назад

Imagine what they'll think in a few thousand years about our scrawling on paper. What are we missing that they'll see?

@patu8010 5 месяцев назад

I wondered if ancient Egyptians had a sense of humor, but I googled the hieroglyph for 10k and it looks more like a bent finger than the one in this video :D

@proloycodes 5 месяцев назад

we all giggled, admit it

@sickcallranger2590 5 месяцев назад

It’s a bent finger, guys.

@tonieslychane 5 месяцев назад

i just came up with a new "socks in the drawer" theorem - could anyone from numberphile team prove it? It is true that when you buy new pair of socks the probability of finding a matching pair in your disorganized sock drawer decreases.

@cam5556 5 месяцев назад

Depends how many colours of socks you have

@cam5556 5 месяцев назад

If there are only 2 colours, the probability is always 100% after three selections, even if you have a thousand of each colour

@m__s_david 5 месяцев назад

cool🌸

@logdroppersavant3683 5 месяцев назад

Oh, bless your heart darling, that right thar is not what one would call a bent finger...

@JohnDlugosz 5 месяцев назад

So how did they work them out, when they didn't have a more powerful system to do it with? We're supposing that the Egyptian Fractions were all they had.

@breathless792 5 месяцев назад

according to something I read a while ago there was one fraction that can't be written like this: (2/3)

@maxrs07 5 месяцев назад

isnt greedy algorithm just euclidean algorithm but instead of pulling gcd number u pull fraction at each step?

@johnfreking6931 5 месяцев назад

How did the Egyptians write pi?

@rainerausdemspring3584 5 месяцев назад

Why on earth haven't you mentioned the notorious odd Egyptian fractions conjecture? Does the greedy algorithm work for odd denominators?

@alanhersch4617 5 месяцев назад

The greedy algorithm works for ALL denominators but isnt optimized.

@rainerausdemspring3584 5 месяцев назад

@@alanhersch4617 Of course. What I mean is: Does the greedy algorithm work if we always take the smallest odd reciprocal? As far as I know this is an open question.

@alanhersch4617 5 месяцев назад

@@rainerausdemspring3584 Oh oop, totally misunderstood.

@tesha8202 5 месяцев назад

Do we count 0-9 or 1-10 ???????

@minamagdy4126 5 месяцев назад

Ancient Egypt did have a concept of nothing, but whether they fully understood it as a quantity of "zero" is unclear, even in later eras where the word was used somewhat more computationally. Counting, therefore, would be 1-10, especially in earlier eras

@fraz071097 5 месяцев назад

Immagine this guys writing the algorithm to know how to translate those in hieroglyphics... Why so fancy with the number skins lol

@colincoulthard3021 5 месяцев назад

It’s *definitely* a bent finger. 😂

@ontheballcity71 5 месяцев назад

A000058 in the OEIS.

@funkydiscogod 5 месяцев назад

1:00 I don't see a bent finger.

@Pfhorrest 5 месяцев назад

Deeefinitely a bent finger and not anything else at all nope not anything else why what were you thinking it was?

@GilCosta1965 5 месяцев назад

stop using commas in numbers. The space is just fine. Look: 1 000 000 23 565 56 236 656 A space. The same space occupied by a comma. You even save time and ink. (at least until all countries adopt the point as decimal separator, like they should)

@GamingDreamer 5 месяцев назад

1:00 ancient Egyptian girls need fun too

@bagelnocat 5 месяцев назад

How your video got stuck at 301 views lol

@Sam_on_YouTube 5 месяцев назад

In the Torah, the number 40 just means "a whole lot."

@BoppanaMath 4 месяца назад

Nice video, Sophie! I just posted another video on Egyptian fractions.

@beepboop204 5 месяцев назад

@andymitchell2146 5 месяцев назад

That is not a bent finger.

@maker0824 5 месяцев назад

There’s an even simpler way to prove that you can always have an Egyptian fraction. N/b=N*(1/b)

@danielyuan9862 5 месяцев назад

3:10 Idk why this rule exists. It seems to just make their lives harder.

@alanhersch4617 5 месяцев назад

@@danielyuan9862 Reading through other comments, an idea brought up was that this was often used to calculate tax, and with that rule, it means you need 1 measuring cup of each size to get any number. So you can measure it all out and visually confirm between all parties.

@graduator14 5 месяцев назад

My ex called it the "bent finger". :(

@unvergebeneid 5 месяцев назад

Maybe I should convince my boss to only pay me 1001 bucks but then convince him that this actually means a bit more than infinity. Although I'm not sure how this works... if there's infinity money, there's also infinity inflation... 🤔