Can you solve the egg drop riddle? - Yossi Elran

  • Published on Nov 7, 2017
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    The city has just opened its one-of-a-kind Faberge Egg Museum, with a single egg displayed on each floor of a 100-story building -- and the world’s most notorious jewel thief already has her eyes on the prize. Can you help the thief formulate a plan that will drop the most expensive egg she can get safely into her waiting truck? Yossi Elran shows how.
    Lesson by Yossi Elran, directed by Artrake Studio.
    Thank you so much to our patrons for your support! Without you this video would not be possible!
    Yuh Saito, Sarabeth Knobel, Quentin Le Menez, Mattia Veltri, Fabian Amels, Sandra Tersluisen, Marcel Trompeter-Petrovic, PnDAA, Jose Fernandez-Calvo, Steph, Zhexi Shan, Gustavo Mendoza, Bárbara Nazaré, Josh Engel, Natalia Rico, Andrea Feliz, Olivier Brunel, Bernardo Paulo, Victor E Karhel, Sydney Evans, Latora Slydell, Noel Situ, Elliot Poulin, Emily Lam, Alex Neal.

Comments • 5 038

  • TED-Ed
    TED-Ed  Year ago +674

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    • vishal adepu
      vishal adepu 9 days ago

      +Kevin Qu 7 it is

    • FOXTR0T1
      FOXTR0T1 4 months ago

      I think you can do it in 7 tries by dividing the building into halves each time.
      Start by dropping from floor 50 if it doesn’t break focus on the top half of the building. Now go to floor 100 it breaks, now 75, it doesn’t, continuing down this halving route you can narrow down the floor after only 7 drops.

    • The Shipmaster
      The Shipmaster 6 months ago

      Idk why but your outro reminded me of Aperture Science from portal

    • Movie Miniac
      Movie Miniac 8 months ago

      This trick can be pulled off using only 7 egg drops
      For an example
      First at 50 and if it breaks the next at 25 then if it breaks at 13 and if it survives at 19 then if it still survives at 23 if breaks then at 21 and if survives at 22. This can be applied for all circumstances. The logic is like Binary Search.

  • BranchKiddo
    BranchKiddo 4 hours ago

    Maybe Should Have Placed A Trampoline in the truck

  • //Masked Messenger//
    //Masked Messenger// 5 hours ago

    Me: *puts tons of pillows in the van* DONE

  • dezouza
    dezouza 8 hours ago

    so the best jewel theif in the world's plan is:
    1: yeet
    2: profit

  • Just4Fun
    Just4Fun Day ago

    If the thief can go in and out of the building with the egg the just charge the the real egg for the fake on and walk out.

  • Mike Klee
    Mike Klee Day ago

    Just throw the top one off and pray

  • BlueAversion
    BlueAversion Day ago

    After watching about a dozen of these it has finally occurred to me that these aren't riddles, they are logic puzzles.
    A riddle is more something such as 'what runs but never walks, has a mouth that never talks?'

    Answer: a river

  • farefouse olly
    farefouse olly Day ago

    move away from the building and test it there.

  • Nine year old
    Nine year old 2 days ago +2

    Easier solution-
    Step 1: steal the top egg and replace it with the replica
    Step 2: leave

  • Anonymous Monkey
    Anonymous Monkey 3 days ago

    that thief is notorious...for her crime against fashion.

  • Aresnal Player
    Aresnal Player 3 days ago


    *carry the egg 100 story egg with u when going down the rope*

  • Alexander wahl
    Alexander wahl 4 days ago

    i wanted a riddle not a math lesson

  • nushi chav
    nushi chav 4 days ago

    You could just drop it from the 100th f no neverind

  • V1
    V1 4 days ago

    what if there were 3 eggs? 4 eggs? ....n eggs?

  • Azzy Land Fan
    Azzy Land Fan 5 days ago

    We are literally helping a criminal

  • Alex van der Plas
    Alex van der Plas 6 days ago +2

    Better to start at 50, then 25/75, then 12/37 or 62/87 and so on. If it breaks you go down, if it doesnt you go up. That will garantee a win in 9 tries.
    Edit: nevermind

    • Floyd Huxtable
      Floyd Huxtable 5 days ago

      Alex van der Plas all good dude 😄

    • Alex van der Plas
      Alex van der Plas 5 days ago +1

      +Floyd Huxtable oh haha my bad. Didnt catch that you only had 2 eggs to test

    • Floyd Huxtable
      Floyd Huxtable 5 days ago

      Alex van der Plas but you only have 2 eggs to test with and they’re both broken. I don’t think you understand the constraints

    • Alex van der Plas
      Alex van der Plas 5 days ago

      +Floyd Huxtable you go to 12

    • Floyd Huxtable
      Floyd Huxtable 5 days ago

      Alex van der Plas so what happens if the next egg breaks from 25?

  • Chelsea Ryder
    Chelsea Ryder 6 days ago

    this should be the easiest. No math required

  • Ian Miscenich
    Ian Miscenich 7 days ago

    Just carry the egg with you as you go down

  • delaneymarie
    delaneymarie 7 days ago

    Put the egg under her shirt. Even the big tough guards won't question if lady is pregnant or not.

  • Dan The Monster
    Dan The Monster 8 days ago

    If i was her I’d just attach a parachute with a bunch of pillows around it and throw it into the truck depends on the wind though

  • finlay dunn
    finlay dunn 8 days ago

    why wouldnt you just repel with the egg?;)

  • Commenter A
    Commenter A 9 days ago

    The real question: Why would we help a thief?

  • R Marsh
    R Marsh 9 days ago

    Who remembers when thieves didn't have baseball bats on their heads and didn't walk around in there disguise in public.

  • BigBearBrads
    BigBearBrads 9 days ago

    Larger intervals would work better. Yes you have more to cover with the second egg, but if you do too many with the first, the durability of the egg will decrease leaving your results inconsistent. You need to drop the egg when it at or near full durability.

  • CorgiLover 162
    CorgiLover 162 9 days ago

    Can't she just hold the egg while sliding down the rope?

  • Alex Ye
    Alex Ye 9 days ago +1

    Or, buy the souvenirs and take them to a less suspicious location for testing.

  • bawse lady
    bawse lady 9 days ago

    😂 And yet people say the math taught in schools is useless

  • Elevox
    Elevox 9 days ago

    We learn math to prevent as from thinking of stealing because we dont have a job but this video teaches us how to steal with math

  • Elevox
    Elevox 9 days ago

    I like how the people here comment funny things entirely different scenarios than the video. And whats funny is its very true

  • Abdelrahman Gamal
    Abdelrahman Gamal 9 days ago +1

    Log2(100) = 7 tries

  • Olegusar777
    Olegusar777 10 days ago

    I thought and, despite the given solution, still think that the correct approach to a problem is to divide the building into halves with each drop. So you start with the 50th floor, then, if it breaks -> 25th, if not -> 75th and so on.
    This solution is obviously less precise, as if for example the egg cracks on first two throws you basically receive next to nothing information on which floor is suitable for the theft; but as it was said too many throws would be suspicious and the solution I wrote above requires twice as less throws to determine the correct floor.

  • Amy June
    Amy June 10 days ago

    The thief kinda looks like a compass for drawing circles

  • Kuriocity
    Kuriocity 10 days ago

    *Why not binary Search???*

  • Martin Anastacio
    Martin Anastacio 10 days ago +3

    14 EGGS???... THAT'S TOO MANY!!!
    First Egg: try it on the 50th floor
    If it doesn't break use the Second Egg on the 75th floor
    If it doesn't break, use the Third Egg on the 88th floor
    If it doesn't break use the Fourth Egg on the 94th floor
    If it doesn't break use the Fifth Egg on the 97th floor
    If it doesn't break use the Sixth Egg on the 99th floor
    If it doesn't break use the Seventh Egg on the 100th floor

    If the First Egg breaks on the 50th Floor, use the Second Egg on the 25th floor


    Half of 50 is 25 so I added 25 to 50, thus making 75
    Half of 25 is 13 (12.5 rounded up), added to 75, thus making 88
    Half of 12.5 is 6 (6.25 rounded down), added to 88 is 94
    Half of 6.25 is 3 (3.125 rounded down), added to 94 is 97
    Half of 3.125 is 2 (1.5625 rounded up), added to 97 is 99
    Well... there's only 1 floor left to try... thus 100

    So we'll need 7 egg replicas
    At the 100th Floor, just swipe the original with the fake... and jump out the window while wearing a glider suit - parachute combo
    Or possibly... just swipe the egg and jump out of the 100th floor wearing glider suit - parachute combo... NO REPLICA EGG NEEDED.

    • Ehab Zabt
      Ehab Zabt 5 days ago +1

      That's my answer too 😀

    • Dime Boskov
      Dime Boskov 8 days ago

      Binary search. Good job man, that's smart 😂

  • Babak Gohardani
    Babak Gohardani 10 days ago

    Solved it by myself

  • cammiecookies
    cammiecookies 10 days ago

    just get some pillows

  • My Tigga
    My Tigga 11 days ago

    Wait but she only has two replica eggs. I'm confused. Could someone explain?

  • Shrektakular 2468
    Shrektakular 2468 11 days ago

    Here's a great invention.

    *a n a i r p l a n e*

  • Benaisha's Studio
    Benaisha's Studio 12 days ago

    My Questions-
    a). Why couldn’t she just carry the egg when she was coming down the rope?
    b). How do all the eggs cost more when they all are the same?
    c). How did no one recognise her?
    d). Why did no one question and check why a truck was there?
    Don’t ask me why I have soooo many questions
    (I’m a 5th grader that's why)

    • Teddy craft & Entertainment
      Teddy craft & Entertainment 10 days ago

      a) The egg is way too heavy. That was said in the video.
      b) the eggs are not the same. They are arranged in ascending order by their value.
      c) she came there hiding. And also, you cant tell just by looking at a person weather she is thief or not
      d) people might think that the truck is filled with eggs and it is their own. And the truck hasn't to stay there long.

  • Charlton Qiu
    Charlton Qiu 12 days ago

    Call the police!

  • Zoe Jordan
    Zoe Jordan 13 days ago

    I got it right👁️👄👁️

  • Roman Chivers
    Roman Chivers 13 days ago

    This is an awful riddle that is exactly what I was thinking I just thought it would be kind of suspicious to drop 14 eggs from a high security building with insanely expensive knees

  • [GD] Domolas
    [GD] Domolas 13 days ago +1

    I thought you were to STOP the thief...

  • Cosmos Cat
    Cosmos Cat 13 days ago

    Or, ya know, just wing it.

  • walter jones
    walter jones 13 days ago


  • King Nutella
    King Nutella 13 days ago

    I don't get how I still understand this

  • Reach Kung fu
    Reach Kung fu 14 days ago +1

    You can steal the egg by telling a guard that another girl is stealing,so just still the egg that is at the 100th floor and jump on a plane

  • king of trolls
    king of trolls 15 days ago

    Can't you use the elevator

  • CoolCreeper39
    CoolCreeper39 15 days ago +1

    *Throws egg at 1st floor*
    *Throws thief at 100th floor*

  • Bongoe Videos
    Bongoe Videos 16 days ago +2

    Why are we helping criminals exactly???

  • - TSURU
    - TSURU 16 days ago

    _maybe take the 100th egg and take it to the truck?_

  • Anbubu ‘
    Anbubu ‘ 17 days ago +1

    buy a parachute

  • Ju
    Ju 18 days ago

    Why Tedx is always wasting time in fantasy which is not even in anyway related to mankind

  • Lucas Mellor
    Lucas Mellor 20 days ago

    It's not very good if there's only ONE egg on each floor is it?

  • Gacha Noob
    Gacha Noob 20 days ago

    wait a sec
    how can a egg be more valueable if it's the same look same weight
    that doesnt make sense
    so take the 1st 1 and go XD

  • ShylieDoesEdits XOXO

    *when the video says it has a single egg displayed on 100 floors*
    Me: *dies*
    Also me before I died: damn that's a lot of floors

  • L Ling
    L Ling 21 day ago

    Can’t she use purple mattress to put in the truck when egg drop

  • Joshua Reynolds
    Joshua Reynolds 21 day ago +1


  • Jennifer Berry
    Jennifer Berry 22 days ago

    Solution say an egg is faulty on the phone . Disguise as an inspector and get the egg make 1 dollar counterfeit and replace do the same for every egg.

    And if your savage blow up the museum when you have all eggs

  • priyansh parakh
    priyansh parakh 22 days ago

    If it's just an egg, I guess she can, I don't know, put it in her backpack or something so she climbs down with it? That way, she can carry multiple eggs with her from the 100th, the 99th, and so on floors

    *Always carry a backpack during a heist, kids*

  • Ava May
    Ava May 22 days ago

    What would happen if the thief took the PERFECT REPLICA and replaced the egg she wanted to steal? She then takes her 'souvenir' back down the elevator, leaves in her getaway taxi, and no one ever knows.

  • Nathan Buchanan
    Nathan Buchanan 23 days ago

    You can do it with Max of 7 guesses. Cut it in half every time. 50,25,12,6,3,2,1. Start at 50 then Add or subtract depending on whether you need to go higher or lower. Works for 100, but idk about other numbers.

    • Ivan Freire
      Ivan Freire 23 days ago

      You are not considering the fact that, once the egg breaks, you cannot use it anymore.

      For example (using your method):
      50th: egg 1 broke
      25th: egg 2 broke
      You don't which one is the highest floor it would not break (might be 1-24) and you cannot test anymore

  • Red Smith305
    Red Smith305 23 days ago

    Take the gift shop egg and sell it for the same as the top floor egg if they really are identical

  • Red Smith305
    Red Smith305 23 days ago

    Drop the 100th floors egg from the first floor

  • Rosie the Catie
    Rosie the Catie 23 days ago

    And this is why I’m not a criminal

    This is impossible for bean brain to do

  • warbubbles
    warbubbles 24 days ago +1

    Joke's on her, though, as there are only 57 surviving faberge eggs. That museum is stocking counterfeits

  • Fridge
    Fridge 24 days ago


  • Thin Thaw Dar Zin -Tracie

    first off, why am i squishing my brain so hard to HELP A CRIMINAL COMMIT CRIME?!?!?!?!?

    AYO FISHBAIT 24 days ago

    Yo just take an egg, switch them out, and leave with the most expensive.

  • Grainne Power
    Grainne Power 25 days ago

    Put the most expensive egg in a backpack then slide on the rope down. : D

  • Azriel Tuangco
    Azriel Tuangco 25 days ago

    or the thief can jump out the window with the egg. plus the thief can have a parachute on

  • Dear Belgiffle
    Dear Belgiffle 25 days ago +2

    *Finally a ted ed riddle video that states the thief isn't me*

  • Dapper Flareon
    Dapper Flareon 26 days ago

    If the fake eggs are perfect replicas, then why not sell them?

  • Gitana Fox
    Gitana Fox 26 days ago +1

    As soon as algebra came in the picture, I knew I wasn't getting an egg. Damn you Easter bunny!

  • Ha Phuong Chau NGUYEN
    Ha Phuong Chau NGUYEN 27 days ago

    The egg hit the center of her head

  • Brownie draws
    Brownie draws 27 days ago

    Why would be a thief in the first place tho

  • Helen Gulelauri
    Helen Gulelauri 27 days ago +1

    Im not helping a criminal

  • Mario Robe
    Mario Robe 29 days ago +2

    The only reason I didn't solve this puzzle is because I don't like helping thieves...

  • Pi
    Pi 29 days ago +1

    Mark Rober just takes some straws and makes a nice structure that wins.
    Randall Monroe keeps the egg inside the chicken, or hatches the egg midflight.

  • Hya & Chris
    Hya & Chris Month ago

    Nice quote, noice

  • Will Gellert
    Will Gellert Month ago

    Why did we help the villain? Welp, I guess I know how to steal eggs now

  • RedGaming_Queen RulezForevrz

    80% talk about he tought us how to steal
    19% talk about egg breaking
    1% is people doing this.

  • Lukeland
    Lukeland Month ago

    *Why Would I Help A Criminal!?*

  • Shailaja Dubey
    Shailaja Dubey Month ago +4

    the girl is so smart she can be a mathematician instead robbing!

  • Shailaja Dubey
    Shailaja Dubey Month ago +1

    burj khalifa left the chat.

  • Kaine Marco
    Kaine Marco Month ago

    This entire scenario is ridiculous. Imagine dropping an egg over and over and over from every tenth floor? Ludacris.

  • Ninja Parakeet
    Ninja Parakeet Month ago

    What universe is this in

  • Gerardo Diaz JR
    Gerardo Diaz JR Month ago

    Why are we helping a thief here

  • The Cool
    The Cool Month ago

    Add cushioning inside the van.

  • Dagogo Dagogo Hart
    Dagogo Dagogo Hart Month ago

    Did it in 8 drops, what's the flaw in my logic. 2,100, 50, 25....basically splitting it in half and going up if it doesn't break and down if it does.

    • sevenbrokenbricks
      sevenbrokenbricks Month ago

      After two downward splits, you have no test eggs left. They both broke.

  • Evelyn Salazar
    Evelyn Salazar Month ago

    She could just use a drone to carry the egg down to her van, hide the controller, and walk to the van without being noticed

  • Levi Truideman
    Levi Truideman Month ago

    Or teach kids not to steal

  • Gurjas Singh
    Gurjas Singh Month ago

    but wouldn’t the egg get damaged everytime

  • daytime skittles
    daytime skittles Month ago +1

    But the real question is if were gods childs y r we helping a Thief

  • Burble Geggy
    Burble Geggy Month ago +1

    Ifted-ed replies to this, I will chew off my keyboard

  • 저그프로토스
    저그프로토스 Month ago

    At first I thought you had an infinite number of eggs. In that case, a simple binary search would do

  • Taavo Lippus
    Taavo Lippus Month ago

    100th floor: pre-cracked egg

  • Xyme INC
    Xyme INC Month ago

    replace the 100th floor egg with a replica and steal the real one and pretend its a souvenir

  • underplayer 508
    underplayer 508 Month ago

    2/3 drop out of floor 25, 50, and 75

  • marsel egan
    marsel egan Month ago

    I.... I... I .... Don't.... What ?