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Can you solve the dark coin riddle? - Lisa Winer

TED-Ed 4 views

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magic trick
Comment from : @Audiole

can you solve the _____riddle?
Comment from : @Audiole

But how do u know the total number of silver coins?😅
Comment from : @xiaoshasong7035

Well simplest solution is to use the “scope reduction “ method, just imagine there was only one silver faced coin before the lights went out Find the solution, increase the scope😊
Comment from : @PeacefulCommunitee

The solution I thought was that we flip all the coins, gold has more density than silver so the gold side will face down so after the toss we can differentiate between the silver and gold side and divide from there
Comment from : @abhhishekpaul7987

This is total BS
Comment from : @DataJuggler

Why is the smile curse
Comment from : @nerestlanorio7259

3:57 You better hope the coin doesn’t pick left
Comment from : @Blueberry186-k9c

For the bonus riddle:brbrOnly arrangements with an odd number of gold coins can be made all goldbrbrFor arrangements with one gold coin:brGSS or SSG → GGGbrSGS → SSG → GGGbrbrFor arrangements with two gold coins:brGGS or SGG: The only possible moves either turn all coins silver or change the formation to GSGbrFrom there, the only possible option is to turn the formation back to SGG or GGSbrbrFor arrangements with no gold coins, a configuration with two gold coins must be reached on the first movebrSSS → GGS or SGGbrbrEssentially, it is impossible to change the parity of the number of gold coins, since any move will either add two gold coins, remove two gold coins, or keep the number of gold coins the samebrBecause the parity cannot be changed, arrangements with an even number of gold coins can never reach the required odd number of gold coins
Comment from : @farnorthskiing

I actually figured this one out brbrSpoilers below but my thought process was pretty funnybrbr"How are you supposed to find the 20 coins the other way around?"br"If the piles don't need to be the same, could I just take a few coins out and make a ton of them silver?"br"What if I just took 20 of the gold and flipped them all to make them silver?"br"But how do I know which ones are gold right now? What if I flipped some silver ones overbrwait a minute"
Comment from : @FlameGoldTabby

Assuming the silver and gold is pure, you could also just bite the coinsbrWhile both metals are relatively soft gold is way softer and it will leave very clear bite marks with less pressure than the silver sidebrSo bite all the coins and feel the bite marks, the side with deeper marks is the gold side, and the opposite is true for the silver side
Comment from : @codygraves509

Final riddle: Pairity rules! If the amount of gold coins is odd, you can make them all gold If even, best you can do is two gold, or pure silver
Comment from : @spote571

HOW A MATH TEACHER EXPECTS AS TO USE MATHEMATICCSSSSSS
Comment from : @TRUSTBOGATSU

what if the gold side is real gold and you can bite it and can tell if its gold sine real gold is soft(sorry for ruining the riddle)
Comment from : @Kelp-u1i

the first ever ted riddle i solved as intended
Comment from : @Noir-Vu

Me drop the coins while flip itbrWizard : so you have chosen DEATH
Comment from : @huyentrangnguyen7314

Every year or so I revisit the playlist of TED-Ed riddles, and somehow this one has stumped me every time 😂😂brAt least I've enjoyed all the "A-HA!" moments I got from this vid lmaobrAt least I
Comment from : @capbarker

2:57 wait, hold on though If you did get all 20 silver coins, don’t you fail because the number of silver coins must be >0? That was one of the rules
Comment from : @shadexvii3975

My solution Get a bucket Fill it with water Put a coin in it each time Since gold is twice the weight of silver, the coin should always landed at the bottom of the bucket with the silver side facing up
Comment from : @jeremysun7365

No Bye
Comment from : @josemv25

I solved it without checking the answer, how smart am I
Comment from : @rahulstephenkerketta8878

Assuming each metal half of the coin has the same volume, since gold is denser than silver and therefore heavier, flipping a coin would always land silver-side up, right?
Comment from : @vegaandaltair

Me: Pockets all the coins so there are zero silver coins on each side
Comment from : @isaac2278-e3k

The solution is to use your glowing eyes and teeth as a flashlight
Comment from : @SlappleBattles

What if the bottom one was silver and when he flipped the pile the top became gold
Comment from : @mubkingotaku

This is so smart
Comment from : @JieYan-z3b

What if you take all 20 silver coins in your hand and flipped which means there is no coins have silver face on upper portion,what will you do now
Comment from : @Divyanshi0956zi

So I know I am like 7 years to late to have a say and all but isn’t also possible to lay down all of the coins on the floor lay them on their side and watch which direction they will fall in cause gold is heavier than silver or for the physics majors there gold has a higher density I checked believe me so if you go ahead and lay all of the coins on their sides one buy one at the end there should be twenty coins who fell in the opposite direction the silver ones in this scenario now that you know which ones the silver ones are you can easily divided them into two piles 10 in each one you know just an logical answer for the ones who aren’t algebra experts and yes I do know that the rules explicitly say to not lay the coins on their sides but I believe this rule was meant to stop you from just balancing all of the coins on their sides except of two because it will make it easier to solve plus I am not laying them on their sides while they are considered in the piles and if that still doesn’t count for you don’t think of it as laying them on their sides think of it as dropping the coin vertically to see which direction it will fall so I believe this answer counts
Comment from : @DrIvanVegapunk

I'd use my headlight eyes
Comment from : @totalmalarky

Wow!
Comment from : @giaphoaian

😢😢😢
Comment from : @mayankchaudhary8128

How many times were those coins put in the bag?
Comment from : @hello_hi1

bro has no irisesbrHES COOKED
Comment from : @ImnotnamedLOL

There's a much easier solution "You must divide all of the coins into two piles Each pile can have any number of silver coins, so long as there are an equal number of silver coins in each pile" All you need to do is make two equal piles, and they'll have an EQUAL number of silver coins in each pile because EVERY coin is silver & gold It didn't specify that the coins had to be be facing silver-side up
Comment from : @mygoldfishrocks

I was going to bite the coins and see which side dented which would tell me that side was gold
Comment from : @blue5slow

lllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll
Comment from : @ericknight325

But wouldn’t he had bought a torch on his adventure there?
Comment from : @islamickidschannel786

Only 4 of the arrangements can be arranged to all gold
Comment from : @THCLottery

2025 solution: watch ted ed 💀
Comment from : @asanokip

3
Comment from : @yibao2

1 make sure of the color of your hatbr2 say the amount of that colour hats there is (1)br3 leave with all the gold
Comment from : @RandomYIRP

I think I have the solution to the problem the answer is that if you kick the coins up in the air it will tell how many gold coins there are and how many silver coins there are
Comment from : @RachelDavigo

Being gold is softer than silver, I would scratch each side to feel which was softer
Comment from : @theghostinthemachine5602

I'm giving myself credit for "flip one-by-one" I succeed when I flip #20 according to the logic in the video
Comment from : @Dexaan

GENIUS
Comment from : @dyno2240

What if you're off by missing a few silver coins?
Comment from : @Paulthored

Go to mordor
Comment from : @maricelevangelista761

That's cool
Comment from : @samnelson9038

Just tell the coins at least one of them have green eyes
Comment from : @sansisfromundertale

There’s no time limit stay in there until your eyes adjust
Comment from : @drakenutting4956

1:39 You've just realized there's a surprisingly easy solutionbryeah, ask the wizard to relight the torches
Comment from : @firegirl4707

I still can’t get this riddle
Comment from : @xiaorongxu-qy7pn

3:50 such a surprisingly easy solution
Comment from : @coolgamer26-z3f

When you remove the 20 coins, you expose the coins that were hidden underneath them Couldn’t that result in more coins silver side up in the large pile?
Comment from : @GrahamJ-ct4ti

Exactly four of the rows can be flipped to have three gold coins
Comment from : @Silverwind87

Can I identify the source and quote this video when I write?
Comment from : @x628uy7eh2

My answer - You said he was exploring , meaning he must have a flashlight , and you showed that the dungeon had rocks, just rub the rocks together to form a fire
Comment from : @richaduey4884

i chose the noether 9000 and banished the wizard
Comment from : @cheesycat1

“You can have them!” “🤗” “But you can’t leave” “🤬”
Comment from : @TheHardestBoiled

It is 2:13am and I'm watching these on a bit of a binge I usually try to solve them, but I haven't been until this one I can't believe my half-awake solution was right! I was so pleased with my reasoning and was praying it was sound
Comment from : @minion-mastr333

After testing it out in my head, the answer to the bonus riddle is this: any of the groups with an uneven amount of gold coins facing up to start will be able to turn all gold, since you need to END with an uneven amount of gold coins brbrI’m only six years late, look at me go!
Comment from : @foxpokemonforever4775

You eat all the coins like Eric Cartman and thus there are none to separate anymore
Comment from : @SwedeRacerDC

This is the similar principal behind the card trick that VSauce taught us
Comment from : @version365

Rule 6 : no flipping coins TedEd : count 20 coins and flip the coins
Comment from : @manasimantri3088

I did not understand the rule at first
Comment from : @Jasmine-u5z2y

This still doesn’t make any sense at all
Comment from : @hamedalaraimi9036

alternate way: wait till you eyes can see fine in the dark
Comment from : @bedrockminecraftiscool341

For the bonus riddle, if the middle coin is gold, its neighbors need to have the same orientation as eachother and if the midle coin is silver its neighbors need to have different orientations from eachother
Comment from : @JamesPrice-rx5ff

What learnt: Brilliant is owned by Ted-Ed brbrRiddle: bfacepalms/b
Comment from : @elianepierre4739

I'm a human not a worker
Comment from : @MerrysEnglishJourney

i would pee on the coins The slight bioluminescence from the heat would give me enough light to see
Comment from : @_TriGN

what if i just grab 20 coins the lights are out he cant see it 😐
Comment from : @Nlneievon

the one with 0 or 2 silver coins
Comment from : @airplaneboy9355

Don t you still have to separate the 2 piles having the same amount of silver facing coins?
Comment from : @mcmobius1

he could have just used his glowing teeth to see the coins
Comment from : @mD11BDYT

There is a little more ways to do it and some of them work even if you dont kow how many are what way
Comment from : @FiseCraft

2:54 But what if you grab all… wait, never mind I just figured it out
Comment from : @alexanderaquino1057

2:35 Because taking a coin is the same as it not being silver!
Comment from : @Kalaphant

1:40 I bREALLY/b Wanted you to say "Surprisingly Simple" XD
Comment from : @Kalaphant

I know one rule was you cant tell the difference but you can still just find the squishier side Im pretty sure gold is soft
Comment from : @SchmipleStudios

Ah, so this is the "dark money" the political talkshow hosts were talking about
Comment from : @apokalypthoapokalypsys9573

Damn I actually solved it, went with probability tho
Comment from : @haroldi6450

Not my Dumba$$ thinking no of coins in both piles have to ne same
Comment from : @Ecstatic-Flash

Flip every coin
Comment from : @wanzeop

for the bonus riddle, S-S-S can't be turned into G-G-G so any position you can reach from S-S-S isn't a solution namely, S-G-G G-S-G G-G-S all the other combinations G-G-G G-S-S S-G-S S-S-G are solutions br brI have a conjecture, I think going from G-G-G to G-S-S is analogous to a geometric rotation, while going from G-G-G to S-S-S is a geometric mirroring It's like having a triangle rotate about its center (intersection of the 3 medians), in 4 rotations (of 2pi/4 each) you reach the initial state again But there isn't any rotation that can let you mirror a triangle If we had suites of 4 (G-G-G-G) it would be a square, 5 a pentagon, etc brBut what if we had 3 states for each node, like gold, silver and bronze? brand what if we had another rule of transformation, I think it's still analogous but it would need more work to prove br brThis reminds me of how np complex problems can be translated into other np complex problems and np complete problems can be written in a way to translate any other np problem, although this problem in particular is p complex I think and I don't understand algorithmic complexity enough to tell you why the analogy works!
Comment from : @Hanible