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

Sign up to be emailed the solution to the bonus riddle: 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!

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

Correction: The Villainous Dr. Schrödinger has developed a Growth Ray and intends to create an army of giant cats *which may or may not be alive*

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

"Giant cat army riddle" *proceeds to show a riddle that has very little to do with cats*

were the cats dead or alive

“Can you solve...” Me: No, but thank you for asking

Step 1: confirm you have green eyes Step 2: ask the control panel to open the door

This is, like, the second TedEd riddle I've actually solved. I'm proud of myself lol

Me: Gets ready to solve the riddle... Riddle: *one of the buttons gets the square root of the number* Me: Imma head out

For the bonus question the lowest number of operations is 7: -3,-3,x2,-3,x2,x2,-3 We just need to work our way backward 25 isn't even, so the last operation has to be -3, which means that you have to be at 28 The fastest way to get there is through two x2s, so that brings you to 7 Can't get there from 11 directly, so we make the same basic move as before. Bringing us up to 10, then down to 5 That we can get to with two -3s

This isn't a riddle about cats at all! It's a math problem! I feel cheated. Moar giant cats!

This is my first time to solve a TED-Ed puzzle. I am glad that I solved it myself, please do more VIDEOS like this! :D

1. Confirm you have green eyes. 2. Ask Mr. Schrödinger to leave.

"Masters of spy-craft".....fell into what I assume is a single damn trap as a whole group.

Boi i woulda just pic the damn lock on the door Super spy my foot

These were some insanely fund riddles to solve! At first I was confused on how on Earth I would get a 2 but when I first tried reaching 36 with 5 and 7, the riddle just unraveled into beautiful math! It was also really fun trying to go through different methods to solve the bonus riddle.

*let's just hack into the thing and put in 2 10 14*

If I was ever in a situation like the one in these riddles I would die 🙃😑

For the bonus riddle, imagine keeping the 11s and 3s separate as you do the math to perform the solution, as if they were separate variables; at the end, you’d wind up with 11 times some power of 2, minus a multiple of 3, which has to equal 25. We can make this easier to work with by using modulus 3 (the remainder when something is divided by 3). This is because if two things have the same result mod 3, you can get from one to the other by repeatedly adding or subtracting 3. 25 mod 3 is 1, while 11 mod 3 is 2; repeatedly doubling the latter will turn the mod 3 from 1 to 2, or from 2 to 1 (since 2*2=4 and 4 mod 3 = 1). Doubling once makes the mods match up, but 22 is smaller than 25; we need to double two more times to get 88. § 88-25=63, and 63/3=21, so 21 3s need to be subtracted from 88 to get 25. But this doesn’t mean we need to do 21 individual subtractions; remember we had to double the initial 11 3 times to get to 88. If we put one of the subtractions before the doubling, it makes the subtraction count for double as well ((a-b)*2=a*2-b-b), and multiple doublings stack with each other. As such, if we put a subtraction before any of the three doublings, it ends up counting as eight (2*2*2=8). Expressing 21 as sums of the appropriate powers of two, we get 8+8+4+1; each one tells us where to put a subtraction to make a total of 63 subtracted with the minimum number of subtractions. Put two before all three doublings, one after the first, and one after the last. This results in the optimal solution being: 11-3=8-3=5*2=10-3=7*2=14*2=28-3=25; seven steps. §Edit, better explanation: First we need to figure out how many doublings we need to do. Since we need to get to 25 by subtracting, we need to get above 25; doubling 11 twice gets us to 22, then 44. However, 44-25 = 19, which is not a multiple of 3, so we can’t get from 44 to 25 by subtracting 3s; doubling a third time gets 88, and 88-25 = 63, which is a multiple of 3.

This is the first TED puzzle i worked out on my own and i feel amazing! I figured I'd find the answer without the no repeat rule, but it was so easy to just go back and fill it out that i did it! this brings validation to my life

I would just throw a yarn ball at the cats. THEN FLEE

This is the first one I've gotten right on my own since the green eye problem!

Well, they're Schrodinger's cats, right? So if you do nothing the the cats will destroy the world and also not.

It took like 15 minutes but this is the first TedEd riddle I've gotten right on my own so I'm happy

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 🤷‍♂️

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

Wait, so are Schrödinger's cats dead and he is bringing them back to life, or are they alive and he is just mutating them with radiation... IDK I guess it's both

I don’t know about the shortest possible route, but for the riddle at the end, here is a solution. From 11, you subtract 3 twice to reach 5. From there, you can multiply by 2 and subtract 3 to reach 7. Multiply by 2 twice to reach 28, then subtract 3 to reach 25. Hope this helps!

It's a nice math puzzle but literally has nothing to do with giant cats, so the riddle could've been named anything

FIRST TED-ED RIDDLE, I EVER SOLVED!! I FEEL SO INTELLIGENT NOW!!

Yeah I can never solve these riddles

There are 32 different ways of solving the puzzle, each a variation, that follows these rules: 1. you must always start with the sequence of +5, +7; 2. you can use what ever sequence of +5's and +7's to get to 36, but being careful for solutions that return the numbers 17 or 22. While still being able to finish the puzzle even with the consequences including 17 or 22 at this step, you'll have to manage the rest of your solution, accordingly to not repeat any of the two (there are 14 solutions with 17 in the beginning of the sequence, and 3 solutions with 17 in the end of the sequence) (there are 4 solutions with 22 in the beginning of the sequence and 8 solutions with 22 in the end of the sequence); 3. follow the only possible sequence from 36, through 2, up to 10; 4. you can use what ever sequence of five +5's and one +7 to get from 10 to 42, but being careful if starting with +7 (because this will return 17) or follow the first press of +5 with a +7 (because this will return 22). As mentioned above, all of the 32 solutions are possible, and only some of the solutions require being careful around the use of numbers 17 and 22. 5. follow the only possible sequence from 42 to 14.

These are fun because it’s just math and a bit of working backwards. You can only use the root button on perfect squares: 4, 9, 16, 25, 36, 49 but no others because the rest go above 60. We need a 2 to start. Since it’s not possible to add 5 and/or 7 to get to 2, it must have been from the square 4. Same with 4 and 16. We would only be able to get to 16 if we had a six. Well we can make a six with 36. Since 5+7=12, if we do that 3 times we’ll get there. 0 +5, +7, +5, +7, +5, +7, √, +5, +5, √, √ = 2 We can’t just add to get to 10, we need another square. We can’t use 25 because 5 has already been used. So then we use 9. To get there is easy. 2 + 7, √, +7 = 10 Now all that’s left is 14. No adding once again and there’s only one more square: 49. 10 is divisible by 5 and 49 is divisible by 7 so if we reach the common multiple of 35, we switch from +5 to +7. 10 +5, +5, +5, +5, +5, +7, +7, √, +7 = 14 All done. As for the bonus one, we can work backwards too. 25 We couldn’t have gotten to 25 by x2 so the last step must have been -3 Step 1: 28 28 can be gotten from x2 or -3 as with all evens Step 2: 14 or 31 14 produces 2 paths while 31 makes 1 Step 3: 7, 17, or 34 Step 4: 10, 20, 17, or 37 BUT 17 has already been seen in an earlier step, meaning the path with this 17 is not as fast and can’t be it. After this, all paths that repeat will be removed. If you try this way and one is missing on my solution, it’s probably a repeat. Step 5: 5, 13, 23, 40 Step 6: 8, 16, 26, 43 Step 7: 11, 8, 19, 29, 46 We hit 11 through one path in seven steps. By reversing the pattern, it’s: -3, -3, x2, -3, x2, x2, -3 This is hard to visualize and even represent on a comment on RU-vid but I made a tree to do this.

Wait, if the room explodes, and he’s in the other room, wouldn’t that hurt him and damage the growth ray? You would risk your life but, you are saving the city. Btw: Eat Your Cereal

Well, for once, we can finally achieve humanity's goal of perfecting genetically engineered catgirls.

Very nice puzzle, solved with great pleasure... At 2:51 you said that the series of 5s and 7s is "somewhat arbitrary" but you didn't mention a very important thing, that you can only start with 5 and not 7, because to make 14 you will need √49 which will give you the same output the second time if you start with 7, which I considered at the beginning while solving the puzzle

The answer to the last riddle is 7 steps. You are supposed to solve it by working backwards from 25, as this greatly reduces the number of cases. When working backwards, the operations are either +3 or /2. One can organize these cases like this: Initial: 25 Step 1: 28 Step 2: 14, 31 Step 3: 7, 17, 34 Step 4: 10, 20, 37 Step 5: 5, 13, 23, 40 Step 6: 8, 16, 26, 43 Step 7: 4, 11, 19, 29, 46 Step 7 is the first step where there is an 11, so 7 is the answer.

Is it weird if I use your videos as a sleeping aid? The guys voice really help my mind relax

Cheese has holes More cheese has more holes More holes means less cheese So more cheese is less cheese

Bonus:11-3-3x2-3x2x2-3=25. The trick is to get to 28 because you can’t multiply a number by two to make 25 with the exception of 12.5 which you can’t reach with only these actions. Here is what you do:11-3=8 8-3=5 5x2=10 10-3=7 7x2=14 14x2=28 28-3=25. You can do it in 7.

Main riddle (math problem, rather) was fun! For the bonus riddle, my best is 7 steps: 11, 8, 5, 10, 7, 14, 28, 25. Anyone find a faster method??

this is the first riddle I actually solved on my own!! I feel so proud, usually i just watch them without even attempting it

I like the puzzles themselves in term of the math and logic but the situations setting some of them up are so hilariously insane.

It took me about an hour to figure out that we can reach 2 by going to 36 (15+21)(and then squaring to get to 6 etc.), after that it was pretty smooth. Really enjoyed solving the puzzle, thanks TED!

11 -3 -3 = 5 5×2 = 10 10-3=7 7x2 = 14 14x2 =28 28-3 = 25 7 moves is fewest? 2019 anyone?

Ted-Ed: can you solve this riddle? Me: you know very well i can't

I already saw some of you riddle videos, but this was the first time I tried one of them myself. And after a frustating time, I solved it! It was incredibly sastifactory, so thumbs up!

My sequence- 0,7,12,17,24,29,36,6,11,16,4,"2",9,3,"10",15,22,27,32,37,44,49,7,"14.". My bonus riddle sequence- 11,8,5,10,7,14,28,25,"22.". (7 moves if "11" and "22" is not taken into consideration since they are the first and last numbers). The trick in solving this kind of riddles is using a tree diagram,where we draw multiple sequences at a time to check which sequence will lead to solution.

Bonus riddle Answer 7 steps: 11 8 5 10 7 14 28 25

The intro of these riddles should be: "Stick around after this episode for a brilliant advertisement."

Did anyone else just realised that the two agent names, Delta and Epsilon, are represented be the letters D and E in the Greek alphabet, and D and E backwards is ED? That's sneaky...

The first number-involved riddle I have ever solved in this series. Wow, I am really glad right now!

Anyone else get the Schrodinger's cat reference?

did anyone notice that part of the answer literally showed up at 1:21 (the first eight numbers)

2:46 her arm just extends out

Nailed it! The sequence of the original additions is really key.

"Can you solve the psychopathic muffin riddle? Find out how to reach the first 5 digit prime number With no repeating digits."

looks like it's a cat-astrophic riddle 😏

This is the first riddle i knew how to solve on the playlist! I'm so proud of myself!

The solution of the Bonus riddle and how to get there: It's 7 moves. (-3, -3, x2, -3, x2, x2, -3) 1. I drew a tree diagram starting at 25, going down left means dividing by 2, going down right means adding 3 (It's exactly the opposite because you're starting at the end) 2. Whenever you hit a non-natural number (e.g. 25/2 = 12.5) You do not need to continue that branch since you're never gonna get natural again. 3. Whenever you hit a number that you already saw somewhere higher up, you do not need to continue that branch since it's just a longer path. (e.g. You could hit 17 by going : +3, +3, +3, /2; but going +3, /2, +3 is one move shorter.) 4. Continue the tree downwards until you see an 11 come up. 5. Backtrace the tree upwards from that 11 and you have your solution.

"Can you solve the..." No, we both know the answer is no.

just put a c4 on the door

I worked out the bonus riddle by doing a reverse breadth first search. Instead of getting from 11 to 25 with the operations x2 and -3, I went from 25 to 11 with the operations /2 and +3. The shortest solution to this can just be inverted to get the shortest solution to the original question. This simplifies the search space because when you run into odd numbers, you only have one option: +3. I was able to figure out all of the paths of length 3, then 4, then 5, then 6, then 7 by hand, eliminating all irrelevant paths that led me to a number I already visited. (For example, I found 25 28 31 34 17 to be one path, but I already had 25 28 14 17: since I already visited 17 in a shorter path, there's no way the longer one could provide an optimal solution.) I concluded that the fewest number of moves is seven. The path is 11, 8, 5, 10, 7, 14, 28, 25.

For anyone who wants the answer to the riddle at the end of the video... The answer is 7 moves (11, 8, 5, 10, 7, 14, 28, 25). You know that ×2 is the only way to go up and -3 is the only way to go down. It's also faster to multiply up than subtract down. You also know that only odd numbers are divisible by 2. Thus, you can't ×2 to get to 25, you have to get to 28 first. To get to 28, you can do 14×2, and get to 14 by 7×2. 7 is odd, so you have to get to 10 first and subtract down to 7. You can easily get to 10 from 11, by first subtracting down to 5, then multiplying by 2. When you put it all together, you get: 11-3= 8, 8-3=5, 5×2=10, 10-3=7, 7×2=14, 14×2=28, and 28-3 =5. I don't actually know if this is right, so if anyone has a solution with less moves, please comment! Edit: the trick is to use multiplication as much as possible and to go backwards

Me: presses random buttons Door: opens Dr whatshisname: wha- Me: 😎

4:27 HE WILL BE AND NOT BE AT HIS BOX,AT THE SIME TIME UNTIL HE IS OBSERVED

this is the first ted ed riddle i have solved nd i'm soooo happy !!

this one was surprisingly easy! i arrived wee bit different at 16, but it was just a matter of adding the numbers to 49 in a different order after

Schrodinger's cats... Love the quantum physics reference 😂

How many of you couldn't solve the riddle?;)

Me : Solves a Ted ed riddle for the first time.. Feels like Einstein😪

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

My logic: I’m going to actually solve this riddle! Step 2: Grabs paper and a calculator. Step 3: try’s to answer questions Step 4: forgets pencil Step 5: rages and to lazy to get up and figure out the problem Step 6: fast forwards video Step 7: gets answer and likes comment in the comment section saying they find the answer without fast forwarding. Step 8; forgets to write step 1 Step 9: Still confused about riddle and how he got the answer Step 10: watches previous video and begin with step 1 again.

I see what you did there with cats and Schrodinger

It’s easier to solve it backwards. The last number we should get is 14. We can get it by adding 7 to 7(other options are eliminated due to various limitations). So we know that after 10 we should get 7(that can be achieved by adding 39 = 7+7+5+5+5+5+5 to 10, and taking a square root of it). 10 can be achieved by adding 7 to 2, taking a square root and adding 7 again, and so on

simple:11 times 2 is 22 -3=19-3=16-3=13- 3=10 -3=7 times 2=14x2=28-3=25

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

How kind that the villain leaves 5, 7, and square route on the keyboard.

The answer to the bonus riddle is 10 steps. Ignoring bodmas, it is 11-3-3×2×2×2-3-3-3-3-3. The riddle is easy but definitely worth answering. I love these small but worthy riddles. Thank you for these small bonuses.

When you see “can you solve” on a video: 87.4%: Just look, see answers 10.1%: Big brain time 2.5%: BONUS RIDDLE 1ST

love your video!!! It must have take more time to make than solving them!!!

Who else watches these riddles but never solves them?

I reached my solution a bit differently. I started from 2 and finished the sequence, before finding how to get 2. I figured that way i could more easily see which numbers not to repeat.

Omg yay I was able to solve this one without help!

Friggin love your riddles

4:39 11-3=8 8-3=5 5x2=10 10x2=20 20x2=40 40-3=37 37-3=34 34-3=31 31-3=28 28-3=25 I did it

Yay, I solved it for about 15 mins before looking at the answer!!! Working backwards is the key.

for bonus riddle: 11 (-3) 8 (-3) 5 (x2) 10 (-3) 7 (x2) 14 (x2) 28 (-3) 25 *flies away

FIRST TIME I CAN SOLVE ONE OF THESE DAMN RIDDLES YASSSSS

Got this one pretty easily

Rare math riddled that I solved. To reach 2, you need SQRT(4) which is SQRT(16), achieved through 6+5+5 from SQRT(36). To reach 10, you need 3+7, where 3 is SQRT(9), and to reach 14 you can't go through 2 or 9 again, so you need 7 which is SQRT(49). Mix up the order of the +5s and +7s to not have repeats.

Finally solved a whole riddle. I kept finishing only half of the others or zero progress at all so this is refreshing. Thank you, Ted-Ed!

He would have made a name for himself. Actually, he was already infamous for bringing horrified thoughts of cats getting poisoned to all cat lovers in the world.

I bet everyone was in the game till 1:01

Don’t know if this is the shortest way per se, but I managed to get from 11 to 25 through this solution: -3, -3, x2, -3, x2, x2, -3 The values after the operations are as follows: 8, 5, 10, 7, 14, 28, 25. Figured it out by going from the solution to the question backwards :)

First ted ed riddle ive ever cracked

Everybody is vibing and stuff but at 0:35 the enter button is on the space key

Solution 1: pop the buttons back in. Solution 2: ask Agent Delta or whoever to hack the display to say "5 10 14"

Nice, got this one. The observation to make is that the only way to get 2 is by sqr 4, since 2 is smaller than both 5 and 7, indicating the importance of the sqr function. 16 can't be directly achieved, but 36 can. After, you add 5 twice to get 16, of which u sqr twice to get 2. The following is just pure intuition, and it helps you make a list of square numbers. I immediately eliminated beginning with 7, as 1 can never be reached (sqr 2 isn't 1), and thus 49 cannot be reached, as square numbers are the only way to sqr a number and still create an integer, and that there were no combination of 5 and 7's which could create the remaining square numbers, I deduced that the sequence must begin with 5. Hence, the sequence went as follows: 5,10,15,22,29,36,6,11,16,4,2,9,3,10,17,24,29,34,39,44,49,7,14. Using algebra to find these combinations of 5 and 7's which add to say 39, denoted by 7y+5x is very useful and speeds up the process.