# 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.

## 100 thoughts on “Can you solve the giant cat army riddle? – Dan Finkel”

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. Yellow Lama says:

Solution: blow up the door

3. doviid says:

Looks like the cat is out of the box.

4. V trashy says:

Second Riddle: Multiply 11 by 2 and then subtract 3 until you reach 23 then multiply 23 by 2 to reach 46 and subtract 3 until you reach 25

5. Alina Nechiporenko says:

This one was hard! I couldn’t do it. This is really cool. I’d love to try something like this in the future.
Edit: I got the bonus puzzle! Press read more if you want to see how I got it.

11-3-3-3x2x2x2x2-3-3-3-3-3-3×2

6. MrSowey says:

For the first riddle:
There is a way that uses less button pressing.
Sequence:
7 14 21 26 31 36 6 11 16 4 2 9 3 10

This way you can reach the cats before the laser 🙂

7. Wakil Hamidi says:

Bonus

Multiply by 2 twice then subtracting by three 8 times multiply by 2 then subtract 3 5 times

8. Amantha Soh says:

i suppose we're perry the platypus

9. Drew Senna says:

I mean like what kind of spy doesn't have any gadget to help them to do stuff

10. Jgaldragon says:

No one said there would be math!

11. PANTHAGANI AJAY says:

Wow!! That was a lot of giant cats 😮

12. Marco Rosi says:

I actually got it, It's like the first one I get😂

13. Aayushi Joshi says:

14. Jack Donegan says:

but the riddle has nothing to do with giants, cats, or armies.

15. Llamagirl R says:

Been watching these for years, this is the second or third one ever that I've gotten. Let's go maths!

16. kylan seats says:

First one I’ve solved 😂😊

17. •Mystiq • says:

I wanna pet them

18. Flekawu III says:

You would think that they could just re attach the keyboard buttons, but no.

19. Julia Ferreira says:

Can’t believe I got it right, educational system not fail after all 🙂

My favorite is agent epsilon

21. XxMeower2008xX d: says:

Me: exists
TedEd Riddles: ima bout to end this mans career

22. Rocskatu says:

This just sounds like an episode of Phineas and Ferb

23. muhammed baasil says:

I used table which adds 7 on x axis and 5 on y axis. It diagonally adds 12 and 2 inclined. Pretty easy to spot 36. Then everything became easy..

24. Hoai Thu Nguyen says:

Do nothing. Why would anyone want to use cats, CATS, of all animals, to terrorize the city? The doctor just need a bunch of normal cats to show up and people would give them everything. At least I would. Probably that's why he failed. His inability to use the cats' existing skill caused those people to try stopping his plan.

25. Lucas Layton says:

I disliked because the title is misleading. The riddles got nothing to do with a giant cat army.

26. Lucie Proskova says:

I thinked you cant press a key twice in a row… i readed it badly

27. Dragon Fighters says:

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

28. Sharktos says:

Finally a riddle that I could solve!

29. Harvey Sun says:

Don’t wprry if you can solve the riddle in time…only the box will be enlarged, not the cats!

30. Michel Genon says:

1:55 0:00

31. Suraya Suraya says:

Narrator: but there’s a problem
Me: OF COURSE THERE IS A PROBLEM!!!

32. Mandeep Prajapat says:

11 – 8 – 5 – 10 – 7 – 14 – 28 – 25
Start from 25 and make a tree for every step this will be shortest branch 😊

33. aneesh mohanty says:

Easy one

For the end riddle; 11-22-19-16-13-10-7-14-28-25
I know the fewest (in the comments) is 7 but this is another way to solve it

35. Henry Lewis says:

11-3×2-3-3-3x2x2-3=25 8 moves

36. Stacy Betz says:

Wait,zero is a non-whole number,so wouldn't the room explode right away?

37. Cupcake 102 says:

he wants to make giant cats

Me to bro

38. Anxious Echo says:

Can I solve the giant cat army riddle?

Ah. Well. No.

39. Warrior89 2.0 says:

I think the answer to the bonus riddle is eight. The solution is 11-3=8
8×2=16
16-3=13
10-3=7
7×2=14
14×2=28
28-3=25

Just find the least number of moves by making a table by doing both operations on the row before it.
11
*2 = 24, -3 = 8
24, 8
48, 21, 16, 5
96, 45, 42, 18, 32, 13, 10, 2
192, 93, 90, 42, 84, 39, 36, 15, 64, 29, 26, 10, 20, 7, 4, -1
Notice that in this row of sixteen numbers(I counted them) we have a 7. If you multiply 7 by 2 twice you get 28. Then subtract 3 to get 25.

So, the path is
11-3=8
8-3=5
5*2=10
10-3=7
7*2=14
14*2=28
28-3=25
In 7 steps, and 8 numbers: 11,8,5,10,7,14,28,25.

The next best solution is
11-3=8
8×2=16
16-3=13
13-3=10
10-3=7
7×2=14
14×2=28
28-3=25

41. Franimatics says:

I just realized its spelled the same as
Erwin Shrõdinger
Im redoing all the riddles cuz im bored

42. Yixuan Lee says:

5-10-17-24-31-36-6-11-16-4-2-7-14. ted ed , ur answer sucks, my answer is only 13steps while yours is 23steps

43. Yixuan Lee says:

11-25: 11-8-5-25 }3 STEPS ONLY

44. Kim Kenneth Villacorta says:

Dunno if this is the best, but my answer to the post challenge is… 11, 9, 7, 4, 8, 5, 10, 20, 17, 34, 31, 28, 25

45. Potato Server says:

Can’t believe i answered it mentally. This is the second riddle i got so far.

46. Yakxter3228 says:

Literally no one:
TedEd:
"……bUt tHeRes a pRoBleM"

47. Wondermix x says:

11×2=22-3=19-3=16-3=13-3=10-3=7×2=14×2=28-3=25!!!

I know it's not the shortest but I bought it was right before I read the comments

48. Jennifer Thomas says:

Solved the bonus riddle in 8 moves reply if you can do better.
Yeh boi

49. AutoManic says:

That is a… uh…. very interesting security mechanism you've got there, Dr. Schrodinger….

I CANT BELIEVE I FINALLY SOLVED A TED ED RIDDLE

51. Alvaldong says:

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

Seven is the fewest possible number of moves

But idk tho could be wrong

52. Majksa says:

i would press Square root and commit suicide

53. Majksa says:

omg, i solved it

54. Majksa says:

BONUS: 11-3 => 8-3 => 5×2 => 10-3 => 7×2 =>14×2 => 28-3 => 25
so if i am right, 7 moves are needed

55. Reese606 says:

Me at school: Watches Ted Ed education videos
Me at home: Watches Tad Ed riddles

56. Mein Feish says:

MATRIX

57. Harsh Soni says:

this is for the bonus riddle
11-3-3=5x2x2=20-3=17×2=34-3-3-3=25

58. Tyler N says:

I just looked at how they solved it at the intro and that was my answer lol

First one I actually solved!!! This is such a fun series

Another possible solution: 5 12 19 24 29 36 6 11 16 4 2 9 3 10 15 20 27 34 39 44 49 7 14

61. fangloi says:

5 12 19 24 31 36 6 11 16 4 2 9 3 10 15 20 25 32 39 44 49 7 14 also work

62. Vitor Games da terra final says:

you get in the room, and you don't

63. Aleko B. says:

Solved in 4 minutes and 22 seconds. Safe to say Dr. Schrödinger is dead… and alive..? 😳

64. A. Zhang says:

I got this one but I didn't do as much thinking, I was smart and also lucky to get it on the first try 😂

65. oussama aqebli says:

i found the first solution and for the other riddle the solution is:
11(-3) 8(-3) 5(*2) 10(-3) 7 (*2) 14(*2) 28(-3) "25"
At least that what i could find :<

66. Mahmoud Hossam says:

Bonus riddle:
11,8,5,10,7,14,28,25

67. phoebe juli says:

At least it’s cats
If anything it’s a little good

68. Chocolate Is Life Chocolate Is Love says:

2-9-3-10-15-20-25-30-35-42-49-7-
14.
I basically did all of this myself and got proud since this is my first time solving a Ted-Ed puzzle.🎉😙

69. Untied States says:

70. Christopher Lara says:

I don't even know how to do square roots

71. Charlie Sullivan says:

Giant litter box cage

72. Luxurdo says:

0:08 the shape is very odd

Very ODD

73. Leela_ _Steele says:

4:36 11-3-3×2-3x2x2-3=25

74. legendhero 45 says:

Thank you for the video! All of you friends are super awesome!

75. Kate Kwai says:

B-but I love cat ;~;

76. Fury Boii says:

Every citizen shall own a pickle…
Gg.. Problem solved

77. Underlord 26 says:

Man invents growth ray, uses it to make giant cats

78. Vantor Vantor says:

the answer was obous sence the ray is top side hit it with a airstike
blow it up
or cut the power

79. Vivianite Hawk says:

Why did you have to break into his base? The cats were on the outside so you could’ve just snuck around the outside and stolen the box of cats 🤷‍♂️

80. Attack Zombies says:

I found another solution which takes the same number of steps:

5 12 19 26 31 36 6 11 16 4 2 9 3 10 17 24 29 34 39 44 49 7 14

81. Howard Chen says:

anyone reminded of the lego ninjago movie?

82. Jealous Pig says:

I ACTUAPLY DID IT ON MY OWN

83. Julius Dolosa says:

Idk how to get the square root …so I'm gonna die early 👍

84. Surecell Laser Dental Aesthetics says:

For bonus riddle
1)11-3=8 2)8-3=5 3)5*2=10 4)10-3=7 5)7*2=14 6)14*2=28 7)28-3=25. That's it. 7 steps

85. Spectrum 0 says:

Is anyone with me when I say! What?

86. Zuber Mesfin says:

87. ChargedCweeper says:

11 – 3 = 8 – 3 = 5 x 2 = 10 – 3 = 7 x 2 = 14 x 2 = 28 – 3

88. Xynnful says:

If Agent Delta is so great, how come he only hacked some of its functionality and not all?

89. Eric Drell says:

This riddle has nothing to do with cats, instead I was tricked into a math problem. I’m calling shenanigans

90. Liza Piashko says:

4:41
11-3-3×2-3-3×2-3=25

91. Itz bubble gum Berry plays says:

Who is watching this and do not even solve the riddle? I am like if you do too

92. PlayBud101 says:

Well if ephsilon looks through the camera for the 2 numbers to get, why didn't he get the code?

93. hamxa says:

1:16 Anyone else noticed whats wrong with first line?

94. Henry Blodorn says:

Literally the only ted Ed riddle I actually solved!!!!!!

95. 21 Matei Zahariev says:

11 -3
8 -3
5 *2
10 -3
7 *2
14 *2
28 +3
25

96. Connor Gaming says:

Step 1: Make a mistake on purpose
Step 2: Escape quickly and wait for the room to blow up and blow down the door
Did i do it?

97. Par Apply says:

I did it! My first ted ed riddle i have solved

98. Nikola Pesic says:

Solution in 20 steps:
5 10 15 20 25 30 35 42 49 7 14 21 26 31 36 6 11 16 4 2

99. yurine hanazono says: