Can you solve the giant cat army riddle? – Dan Finkel


The villainous Dr. Schrödinger
has developed a growth ray and intends to create
an army of giant cats to terrorize the city. Your team of secret agents has tracked him
to his underground lab. You burst in to find… that it’s a trap! Dr. Schrödinger has slipped
into the next room to activate his device and disabled the control
panel on the way out. Fortunately, your teammates are
masters of spy-craft. Agent Delta has hacked
into the control panel and managed to reactivate
some of its functionality. Meanwhile, Agent Epsilon has
searched through surveillance to find the code for the door: 2, 10, 14. All you have to do is enter those numbers
and you’ll be free. But there’s a problem. The control panel has only three buttons: one which adds 5 to the display number, one which adds 7, and one which takes the square root. You need to make the display output
the numbers 2, 10, and 14,
in that order. It’s okay if it outputs different
numbers in between, but there’s no way to reset the display, so once you get to 2, you’ll have to continue
on to 10 and 14 from there. Not only that, Agent Delta explains that there are other traps
built into the panel. If it ever shows the same number
more than once, a number greater than 60, or a non-whole number, the room will explode. Right now, the display reads zero,
and time is running out. There’s only one way to solve the puzzle,
with a few small variations. How will you input the code to escape
from Dr. Schrödinger’s lair and save the day? Pause the video now if you want
to figure it out for yourself! Answer in: 3 2 1. You look over your options. Adding 5 or 7 increases the number, and the square root button
will make it smaller. But there are only a few options
where you can use that button: 4 9 16 25, 36, and 49. You’d love to make 4 or 16. Then you could hit the square root button
once or twice to get 2. But you can’t make either with
just the 5 and 7 buttons. What will you do? You look at the other possible options for
numbers you could take the square root of. Nine you can’t reach. Twenty-five and 49 would take you back to
5 or 7, and you can already get to each
of those. Thirty-six is your only option. You add 5, 7, 5, 7, 5, 7, and then hit the square root button. Why that series of 5s and 7s? It’s somewhat arbitrary, but you know that you want
to avoid 10, 14, and perfect squares, since you’ll need them later. This gets you to 6. Does that help? Looking at your options,
you see that 16 is now in your sights. You add 5 twice more to reach it. Then hit square root twice. That gets you to 2. You’re on your way! Now to 10. You can’t get straight
there through addition alone, so you’re going to have
to reach another square. Taking the square root of 9 or 25 would
get you to a good place, but it turns out that 25
is unreachable from 2. So you add 7 to get to 9, then take the square root again. That gets you to 3. Adding 7 again makes 10. Finally, you need to reach 14. Thinking backwards, you imagine where
you could be before 14: 7 or 9. But 9 won’t work because
you’ve already used 9. However, you could get to 7
by reaching 49 first. You add your way towards it, being careful not to hit any
of the numbers you’ve hit so far. You thread your way carefully, adding five 5s and two 7s. Then, square root to 7, and add 7 more. The door opens,
and you’re out of the trap. Thanks to your problem-solving skills, your team gets Schrödinger’s cats out
of the box in the nick of time. As for Schrödinger,
you can be certain of one thing: he’ll be spending quite some
time in a box of his own.

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100 Responses

  1. TED-Ed says:

    Sign up to be emailed the solution to the bonus riddle: https://brilliant.org/tededm2s3/! Also, if you sign up for a PREMIUM membership using one of our links, you will get 20% off the annual fee. Riddle on, riddlers!

  2. BurningButter says:

    By the title GET A GIANT DOG

  3. sanjib banerjee says:

    Answer :22, 19, 38, 35, 32, 29 and 25

  4. lavatown mafia says:

    bonus riddle answer=11-3-3•2-3•2•2.

  5. lavatown mafia says:

    11-3-3=5
    5•2=10
    10-3=7
    7•2=14
    14•2=28
    28-3=25
    easy anybody else get the bonus riddle right?

  6. Pibix 19 says:

    7, 14, 21, 26, 31, 36, 6, 11, 16, 4, 2, 9, 3, 8, 13, 18, 25, 5, 10

    This one that I came up with works

  7. nowonmetube says:

    (((((((11-3)-3)*2)-3)*2)*2)-3) = 25

  8. Paul Cicero says:

    5-12-19-24-31-36-6-11-16-4-2-9-3-10-17-22-29-34-39-44-49-7-14 also works 🙂

  9. Hoanggiang Ha says:

    11 -3
    8 -3
    5 x2
    10 -3
    7 x2
    14 x2
    28 -3
    25

  10. Spector 181 says:

    1. Confirm you have green eyes.

    2. Ask Mr. Schrödinger to leave.

  11. Ronald Matos says:

    Me: (solves riddle)

    Schrodinger: (grows cats while I'm still trapped)

    Me: FML.

  12. Branana9 - SuperBran says:

    If I was the bad guy I would smash all the keys so there is no more functionality on the keys so no one can get in

  13. Unnamed Skateboarder says:

    First one I solved legit

  14. RandomKid 394 says:

    Bonus Riddle answer (I Think)

    11-3=8
    8-3=5
    5×2=10
    10-3=7
    7×2=14
    14×2=28
    28-3=25

  15. Thomas Thieke says:

    Shrodigners cat 😂

  16. tuobaowt says:

    Agent Epsilon-
    Me: EPSILON 11 CODENAMED NINE-TAILED-FOX HAS ENTERED THE FACILITY

  17. aRandomPersonOnTheInternet says:

    First ever riddle that I solved with a different answer to the video!

    We take the square root of 0 which is 0 it’s the same number the computer explodes in a blast exploding the doctor and us. At least we’d die heroes

  18. Halo Vail says:

    5, 12, 19, 24, 31, 36, 6, 11, 16, 4, 2, 9, 3, 10, 15, 20, 25, 30, 37, 42, 49, 7, 14.

    The order of addition doesn't matter. But what you square does.

  19. Roy Daquilanea says:

    11, 22, 19, 16, 13, 26, 23, 20, 40, 37, 34, 31, 28, 25. my answer's # of moves: 13
    edit: i didn't use the solution to find the answer

  20. Steffi Bernice Sarrosa says:

    Honestly, I would be fine with big cute fluffy cats roaming around……..

  21. McKenna Lien says:

    i don't even know why I'm watching these complicated math riddles when I can't even walk

  22. Zack Gamers says:

    5,12,19,24,31,36,6,11,16,4,2,9,3,10,15,20,27,32,37,42,49,7,14 also done it

  23. Concepcion Ponce says:

    JUST TELL THE GUY TO HACK IT AGIEN

  24. MarkToons HD says:

    Break down the door!!

  25. Prakash Kumar says:

    My Solution:

    To get 2:

    +5, +7, +5, +7, +5, +7. sqrt, +5, +5, sqrt, sqrt

    To get 10:

    +7, sqrt, +7

    To get 14:

    +5, +5, +5, +5, +5, +7, +7, sqrt, +7

    It's the same as the video solution as well. Summarized version

  26. Prakash Kumar says:

    Bonus problem solution. The key to this question is working backwards. It is easier and more logical when you work backwards.

    Full solutions below (including bonus and original problem with thinking process):
    This is essentially a 2 working problem. But repeating it makes it 7 working

    Step 1: Make number even
    Step 2: Divide when possible

    So only available operations is divide by 2 and +3. 25 to 11

    25+3 = 28(To make it even. So that division is possible)
    28/2 = 14(Divide when you can divide)
    14/2 = 7(Divide once again as you want an odd number to find 11)
    7 + 3 = 10(Get even number for division)
    10/2 = 5(Divide when you can)
    5+3 = 8(11 is in sight)
    8+3 = 11 (shown)

    Now do the opposite,
    Divide is multiply
    plus is minus

    11 -3 = 8
    8 – 3 = 5
    5 * 2 = 10

    10-3=7

    7 * 2 = 14

    14 * 2 =28

    28-3 = 25

    The original problem:

    Solution:

    To get 2:

    +5, +7, +5, +7, +5, +7. sqrt, +5, +5, sqrt, sqrt

    To get 10:

    +7, sqrt, +7

    To get 14:

    +5, +5, +5, +5, +5, +7, +7, sqrt, +7

    Same solution as video but summarized. There is also an alternative but requires more steps.

    The key to that problem is essentially getting a perfect square. Forcing your way to a perfect square will be beneficial. Whatever step you do must help you to get a square

  27. Muhammad Rifqi Abdillah says:

    Ah'll try the bonus riddle
    11-3=8
    8-3=5
    5*2=10
    10-3=7
    7*2=14
    14*2=28
    28-3=25

    So the total operation is 7.

  28. Donut And Ava says:

    But I love cats, and you made all those super powers irl videos, so meh…..

  29. Shaq Fu Kenny says:

    11-8-5-10-20-40-37-34-31-28-25?

  30. Rafael Mejico says:

    Just use a laser pointer it will do the job right

  31. Dragon Dawg says:

    11 – 3 = 8
    8-3=5
    5×2=10
    10×2=20
    20-3=17
    17×2=34
    34-3=31
    31-3=28
    28-3=25!
    9 moves!

  32. Cheza Rosanna says:

    i solved it but i got a different series of numbers

  33. Millie Edits says:

    When you don't what the square root symbol means so you search it up-

  34. Entity Valkyrie 2 - Fixing Your Flags version 2 says:

    Found alternate solution, but that one includes numbers > 60, so it is not a true solution
    0, 5, 12, 17, 22, 27, 34, 41, 46, 51, 56, 61, 66, 71, 76, 83, 90, 97, 104, 111, 116, 121, 11, 16, 4, 2, 9, 3, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 77, 84, 91, 98, 103, 108, 113, 118, 123, 128, 133, 138, 143, 148, 153, 158, 163, 168, 175, 182, 189, 196, 14

  35. Diamond’Panda YT says:

    The last riddle u can do 7x2x2-3 and u get 25 😂😂

    Like if u got that one
    👇🏻

  36. Mekacz says:

    I'm getting powerpuff vibes

  37. Brandon Williamson says:

    11x2x2-3-3-3-3-3-3-3-3×2-3-3-3-3-3

  38. Brandon Williamson says:

    answer to bonus riddle

  39. Luka Živoder says:

    I got 5-12-17-22-29-36-6-11-16-4-2-9-3-10-15-20-25-32-37-42-49-7-14

  40. Cj Cola says:

    11 8 5 10 7 14 28 25 8 moves

  41. Darshan C says:

    Just add a c4

  42. SignedTundra Gaming says:

    Bonus Riddle is easy. The Lowest number of moves is 3
    Edit: Nvm. I thought it was the power of 2.
    Edit the Second: The true answer is seven.
    11 -3 (1) = 8 – 3 (2) = 5 x 2 (3) = 10 -3 (4) = 7 x 2 (5) = 14 x 2 (6)= 28 -3 (7) = 25

  43. The one who sucks says:

    How ironic is it for you to be a supervillain that loves cats, and name yourself Schrodinger

  44. Gerardo Trinidad says:

    THIS IS THE FIRST TED ED RIDDLE THAT I SOLVED WITHOUT HELP!!! HAHAHA THANK YOU TED EDDC

  45. Marla Dickens says:

    CATS? CATS? YOU MEAN THE AFRAID OF CUCUMBERS CATS?

  46. Rocco :D says:

    I know the answer
    But I won’t say.

    Probably because I don’t know the answer.

  47. Kaitlyn Oh says:

    If you’re masters, you should’ve posted a lookout.

  48. Joshua Leano says:

    1:23 why does this guy have one leg?

  49. X Eris250 X says:

    1:18 How can they repeat number 5 twice?

  50. BlazePlayz YT says:

    My solution:

    5, 12, 17, 22, 29, 36, 6, 11, 16, 4, 2
    9, 3, 10
    15, 20, 25, 30, 35, 42, 49, 7, 14
    Edit: Oh, I guess I have a very similar solution,

  51. Shreeya Mittal says:

    11,8,5,10,7,14,28,25. This was pretty easy!

  52. Bruce Seitanides says:

    11-3-3=5 5*2=10 10-3 = 7, 7*2 = 14 14*2= 28 28-3 = 25

  53. BlazePlayz YT says:

    For the bonus riddle:
    11, 8, 5, 10, 20, 40, 37, 34, 31, 28, 25
    Long solution but still works, I'll try finding a smaller solution later.

  54. Jerico Dizon says:

    I haaaaaaaaaate tedes

  55. 69 subscriber no vid Challenge says:

    What kind of computer keyboard has +5 and +7

  56. Sophia Nguyen says:

    Step one: get catnip

    Step two: wait.

  57. Danna Mleon says:

    Answer:

    Give the job to the other guys

  58. THERAFMASTER says:

    Dr. Shrodingher…Hahahahhahahaha

    I know I probably spelled that wrong

  59. nathan concord says:

    I know how to kill the cats water!

  60. Don’t Respond says:

    This is the first of your riddles I actually solved

  61. Don’t Respond says:

    BONUS QUESTION: take away 3 from 11 until you get 5, times it by 2 to get 10, again to get 20 and again to get 40 then take away 3 until you get 25, (10 moves)

  62. The Bound Bowman says:

    Are math problems really riddles?

  63. Gao Industries says:

    Isn't Schrodinger's cat like where you out a cat in a poisoned box and you don't know if it's dead or not unless you open the box? Like quantum probability?

  64. Patrick Vicente says:

    The riddle's got nothing to do with cats its about numba's

  65. Zanonymous Ruiz says:

    I love this particular brand of problem- Fun brainteaser, and it actually got me thinking for once 😂💜💜💜

  66. Ynw chives says:

    Bonus riddle answer 11×2 = 22 -3 -3-3-3-3×2×2-3

  67. Gary Lu Productions says:

    Before I watch the solution, my answer is 0 5 12 17 22 29 36 6 11 16 4 [2] 9 3 [10] 15 20 25 30 35 42 49 7 [14]
    Aside from that, that is the strangest keypad I have ever seen. Why does it have a square root button?

  68. Gary Lu Productions says:

    For the bonus riddle, the best solution I was able to find was 7 moves.
    11 8 5 10 7 14 28 25

  69. Gaming Rob12 says:

    I get in the video then the first thing I see is “is the cat dead or alive”

  70. Jay Morlow says:

    Yay first somewhat difficult riddle I've gotten on this channel

  71. Titanic says:

    is a giant cat really so bad?

  72. Titanic says:

    Ya don't need to. Get out of the room, get a rock on a string or something, and swing it wildly. Chances are it will hit buttons in an order that will output a non-whole number, a number greater than 60, or a number that was entered before… BOOM. THE ROOM HAS EXPLODED, AND THE DOOR IS PROBABLY DAMAGED.Now you can just bash it down.

  73. Titanic says:

    Ya don't need to. Get out of the room, get a rock on a string or something, and swing it wildly. Chances are it will hit buttons in an order that will output a non-whole number, a number greater than 60, or a number that was entered before… BOOM. THE ROOM HAS EXPLODED, AND THE DOOR IS PROBABLY DAMAGED.
    Now you can just bash it down.

  74. Winson You says:

    Bruh the answer is at 1:22 LOLOL

  75. UnitedEarthEmpire says:

    Its no fun a riddle video tell the answer right away…

  76. Kyan Azgour says:

    For the second riddle, it's -3, x2, -3, x2, -3, -3, -3, -3, -3, -3, -3.

  77. InfiShades says:

    OMG I ACTUALLY DID IT!!!!!!

  78. gowtham unique says:

    11 8 5 10 7 14 28 25
    You can solve it with a C program
    Perform BFS traversal on State space tree.

  79. Keith Lukens says:

    I can't know thismcause I am in fifth grade and don't know what the square route does comment on this if u know what it does

  80. Poopy says:

    I would hire people to fix the machine

  81. Gman197 Blair says:

    Here’s my way of solving the bonus riddle.
    11 – 3 = 8 x 2 = 16 – 3 = 13 – 3 = 10 x 2 = 20 – 3 = 17 – 3 = 14 x 2 = 28 – 3 = 25

  82. Purple Potato says:

    For extra riddle my best is 7: 11 -3 -3 x2 -3 x2 x2 -3 boom! Tell me if you got any better

  83. Jay Pi says:

    Once 2 is reached everything's much easier

  84. Tom Lever says:

    I'm reporting this video to YouTube. The "GIANT CAT ARMY" was clickbait.

  85. Plague Doc says:

    One of the few ted riddles that I solved exactly right, feels so satisfying 🙂

  86. Treehouse Bros says:

    I follow da wae of da recommend

  87. Emprendedores Digitales says:

    i thought you couldnt get to 25

  88. Dhairya Umrania says:

    11-3-3=5
    5*2=10
    10-3=7
    7*2*2=28
    28-3=25

  89. Shend Osmani says:

    Schrodinger?
    I thought Schrodinger put cats in boxes with bombs.

  90. junnie says:

    i’m so happy i solved it cuz i can’t solve any of the other riddles, but to be fair this one’s more math than logic or strategy and that’s probably why i could do it lol

  91. Rosy Chan says:

    Bonus question answer:

    11 minus 3 two times equals 5, 5 times 2 three times equals to 40, 40 minus 3 five times equals to 25.

  92. I I says:

    Hehe…
    Schrodinger’s cats

  93. Ayush A.K says:

    I think answer is 11-8-5-10-20-40-……-28-25

  94. Wayne Quach says:

    He didnt even solve it if u look at rule 4.a) it says u cant use the same number twice but when he got 16 he used +5 twice

  95. Elijah Morris says:

    1:22 boom, I did it

  96. bacon_ lettuce_tomato says:

    I honestly never know where the riddle is going until the second they start explaining the riddle

  97. __ says:

    Anyone plays the battle cats?

  98. The left upright at soldier field says:

    Problem at the end:
    11-8-5-10-7-14-28-25

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