# Can you solve the sea monster riddle? – Dan Finkel

According to legend,

once every thousand years a host of sea monsters emerges

from the depths to demand tribute from the floating city of Atlantartica. As the ruler of the city,

you’d always dismissed the stories… until today, when 7 Leviathan Lords

rose out of the roiling waters and surrounded your city. Each commands 10 giant kraken, and each kraken

is accompanied by 12 mermites. Your city’s puny army

is hopelessly outmatched. You think back to the legends. In the stories, the ruler of the city

saved his people by feeding the creatures

a ransom of pearls. The pearls would be split equally

between the leviathans lords. Each leviathan would then divide its share

into 11 equal piles, keeping one, and giving the other 10

to their kraken commanders. Each kraken would then divide its share

into 13 equal piles, keeping one, and distributing the other

twelve to their mermite minions. If any one of these divisions left

an unequal pile or leftover pearl, the monsters would pull everyone

to the bottom of the sea. Such was the fate

of your fabled sister city. You rush to the ancient treasure room

and find five chests, each containing a precisely counted number

of pearls prepared by your ancestors

for exactly this purpose. Each of the chests bears a number

telling how many pearls it contains. Unfortunately, the symbols they used

to write digits 1,000 years ago have changed with time, and you don’t know how

to read the ancient numbers. With hundreds of thousands of pearls

in each chest, there’s no time to recount. One of these chests will save your city and the rest will lead

to its certain doom. Which do you choose? Pause the video to figure it out yourself. Answer in 3 Answer in 2 Answer in 1 There isn’t enough information to decode

the ancient Atlantartican numeral system. But all hope is not lost, because there’s another piece

of information those symbols contain: patterns. If we can find a matching pattern

in arabic numerals, we can still pick the right chest. Let’s take stock of what we know. A quantity of pearls that can appease

the sea monsters must be divisible by 7, 11, and 13. Rather than trying out numbers

at random, let’s examine ones that have this property and see if there are any

patterns that unite them. Being divisible by 7, 11, and 13 means that our number must

be a multiple of 7, 11, and 13. Those three numbers are all prime,

so multiplying them together will give us their least

common multiple: 1001. That’s a useful starting place because we now know that any viable

offering to the sea monsters must be a multiple of 1001. Let’s try multiplying it by a three digit

number, just to get a feel for what we might get. If we try 861 times 1001, we get 861,861, and we see something similar

with other examples. It’s a peculiar pattern. Why would multiplying a three-digit

number by 1001 end up giving you two copies

of that number, written one after the other? Breaking down the multiplication

problem can give us the answer. 1001 times any number x is equal

to 1000x + x. For example, 725 times 1000 is 725,000,

and 725 x 1 is 725. So 725 x 1001 will be the sum of

those two numbers: 725,725. And there’s nothing special about 725. Pick any three-digit number, and your final product will have

that many thousands, plus one more. Even though you don’t know how

to read the numbers on the chests, you can read which pattern of digits

represents a number divisible by 1001. As with many problems, trying concrete

examples can give you an intuition for behavior that may at first look

abstract and mysterious. The monsters accept your ransom

and swim back down to the depths for another thousand years. With the proper planning, that should give you plenty of time

to prepare for their inevitable return.

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I actually got this.even though I know no one will believe it took 17 min

i got 20% off

This is one of those few times multiplication actually is useful.

Let me guess is the thousand year curse gonna happen in April?

This may have been the first time I was able to solve a Ted Ed riddle

Brightside:who is the killer?

Ted-ed:you're adorable

I am disappointed. This had nothing to do with sea monsters. This was a word math problem. We are not in school anymore.

loophole, they dont use denery system, instead use binary or someother

Eat Your Cereal

easy! It took me 10 minutes!

yay finally a riddle that i solved

doesnt this only work in a decimal system?

what if the ancestors didnt use a decimal system.

I rule a city?

Welp, everyone is already screwed in that caseOr just take one chest, count 1001 pearls and leave the rest for the future.

But what is that condition "The ancient numerical system was base ten" actually represents?

This fails if the ancient notation was not decimal ;-).

My brain just melted

King: "No problem. I just need my calculator which is in my … Uh … airplane. Yeah, that's right. Wait for me here, I'll be right back."

The city should float to a different address so the sea monsters can't find them.

Damn i actually got this one

Some folks said they should remember how to read the 1,000 year old numbers. You still gotta do the math to know what is the base number that is a divisor of the number of pearls in the chests. Once you know that, the symbols are easy to work out. You don't know how many groups of monsters will show up next time, anyway.

What is really tough, however, is planning how to communicate to people 1,000 years into the future. Sheese, we can't even agree on what the writers of the Constitution meant, and that was only about 200 years ago. Also look into the methods they are trying to devise to communicate to people in the far, far future that nuclear waste is buried in certain locations and that people should stay away, and read, "A Canticle for Leibowitz."

CHAAARRRRGGGGGEEEEEE!!!!!

Bold of you to assume that the ancient people used a decimal system

Great riddle. How did you come up with it?

what if they don’t use base 10…

It's literally 1 am….what am I doing?!

Yo she hot

This is the first riddle I actually solved before finishing the video.

This isn't a riddle. It's a word math problem

this is a BIG BRAIN channel

Plot twist: The monsters aren't patient and attack the city of Atlantartica before you finish solving the math, thus making Atlantartica non existant. Atlanartica is too far away from land for it to be recorded, so it is lost from history.

Plot twist: What if the ancient number system wasn't base 10?

this is the easiest riddle ive solved so far. 🙂

Ok. Here is my reasoning

7x11x13=1001

Since 1001 multiplied by any number have the same start and end. Ex. 1001×24= 24024. Then the Ill choose the one where the chest has the same symbols in the beginning and end which means the right chest is the one above the timer

Edit: Oh my gosh. This is the first time I got a ted ed riddle right on the first try. Yay

Legends say in another 1000 years the monsters will be hunted by submarines

Plot twist: ancient people use 12 numbers instead of 10 numbers

interesting riddle and explainationMe: meh

That was easy

Hey, i actualy solved this one!

Me brain big.

I would have solved this with ease if I was informed that the ancient numeric system was a decimal system. I was very confused as I was unaware if this was decimal or if it was binary or hexadecimal

You know the sea monster

The horses name is friday

Someone must’ve dropped a pearl, now we have a new virus.

TED-Ed: Can you solve the riddle?

Me: Well seeing how the symbols are in the same three symbol sequence, my ancestor must have meant that that chest is the one to be divided in equal parts, much like the serpents' culture.

Ted-Ed: Actually, its math.

Me:…

there are two that is divisible by 1001 the heck u din't give us the answer

Moral learnt…

VISIT THE TREASURY AT LEAST ONCE A YEAR OR YOU ARE GOING TO GET KILLED BY SEA CRACKERS OR WHATEVER

Idk if the math is done right though. The amount the biggest monster receives is different from the kraken because the kraken has to redistribute their earnings after the big one redistributed. Same with the kraken with the smallest monster. Correct me if I'm wrong, it's a hunch

Basically 2020 so far

Wow, I was actually able to solve this one! 😀

Really tough problem,

took me almost 480p for few seconds.

Because that chest follows the repeating pattern you are 100% sure it is a multiple of 1001. I think I get it. Now I need some rest and an aspirin.

Easy,perfectly like what i guess XD

Just take 1001 pearls and give them ?

I got to the 1001 part but then I just gave up

assuming the ancient system was base 10 too….

The short answer is, no. I cannot.

As soon as I had 7x11x13 = 1001, it was so easy to solve. Choose the chest with its first three digits being the same in order as the next three digits.

It would be more interesting if we didnt know that this system was base ten ?

Doesn't 0 work i mean its even and divisible by all the numbers?

For the first time of the history of watching TED-Ed Riddles ~~~~ I actually solved this one!!

Why would we assume they use a base 10 numeral system?

I love at the quotes at the start of videos,they intrigue me every time .

I'm sorry, but before delving into the mathematical process, my first thought was take the unopened chest, because if your ancestors truly prepared for this, all the chests should hold the necessary amount of pearls. But since you, the ruler didn't believe in the myth, it's likely your treasurer didn't either. So all the opened chests will have an amount of missing pearls, because someone opened them and took them to do other useful stuff than feeding monsters. Only the unopened chest can save you. ?

First half: Here's a problem that should be easy.

Second half: BUT THEN YOU CAN'T [insert conundrum here]

Well ……. i was able to solve the riddle

I hereby declare myself smarter than Einstein

If I was the princess and had to do that maff 1:22

I solved this is by assigning each symbol with a letter. Then I replaced each letter with one of 3 shapes. Square, triangle, and circle. Square for the first number and ones alike. Triangle for the second number and ones alike. And Circle for the third. Finally, I replaced each shape with any number from 1-9 and divided each set by 7,11, and 13 ??

TED-Ed, I thought I already told you this

the answer is still no

I got readily close I found character patterns and lcm lols. But I didn’t put two together

I FINALLY SOLVED A TED ED RIDDLE!!! SOMEONE GIVE ME A HIGH FIVE!!!

I'm so proud of myself. This is the first Ted-Ed riddle I could ever solve without the answer!

Wait…if the city is floating (not anchored) can't they just float where it's inhabitable for monsters in the next thousand years?

Hold on a second, another underwater theme park for FREE?

Best riddle ever seen

I was able to get the answer, however, I used a somewhat different method. I would like to know if my method just happened to work in this lone case, or would this also work in any case? And Warning! If you didn't solve it yet, and want to, don't read ahead!

What I did was just randomly assign a number to each symbol, and then I would divide by 7, then by 11, then by 13. I tested each chest. Only one of the chests didn't have any remainders, so that was the answer, and I chose that chest with that pattern. Is that also an ok way to do it? Or does that seem like it works just in this one case?

This was fairly easy TBH!

Wow, I everyone saying this was the first one they got right, this was the first I got wrong (>ヮ<)

1:55 how does the second chest have more than the first but less than the third? The first and third start with the same digit but the second does not. There’s no possible number that could fall between the first and third without also having the same starting digit. This means the numbering system from long ago was much more complicated and the selected chest might not be correct.

I picked the right chest by guessing, IM SO EXCITED!

I got it right. I knew it had something to do with 1001 and just a bit of pattern recognition.

Holy cow I actually got it right? I thought the same if you can't read the number symbol but it is a even divide the symbols would've to repeat itself.

2:29

Arabic numerals?

But if you aren't suppose to give mermaids three digit number of pearls? For example the should get only 3 pearls per mermaid, so than you are looking for 3003 chest, and this is not the one we have picked in the riddle.

They could’ve just gave them 1,001 pearls.

Answer:

Dump the contents of the chests onto the floor and pick however many pearls you want.

13x11x7=1001 pearls

Each creature gets 1 pearl.

Plot Twist: The levaiathons are tacoes

What if they used base 8 or 12 or not base 10 for the numbers?

At 3:00, you say that because 7, 11, and 13 are all prime, the answer must be a multiple of 1001. That's correct; however, since the piles must be subdivided, the primeness of the numbers doesn't matter. For instance, if it were 2 piles, divided into 5 piles, divided into 10 piles, the answer would have to be a multiple of 2*5*10=100, not just 2*5=10.

Love this video series!

"Can you solve the…"

No. I can't. We've been through this. Tens of times. I Cannot. Stop asking.

Still gonna watch the video though lol

I would give them all 5 chests and while they spent a very long time doing all the math my measly army would paddle us to safty somplace not in the middle of an ocean full of extortionist lizard monsters. Beach my city on a real landmass and be forever remebered as the king who solved the problem for eternity

God dmn

Just make your guards count 1001 of them

It's gonna take less time than solving the riddle.??

Plot twist: Ancient Atlanartica used base 6.

These riddles are not meant to be solved – a key piece of information was given after the (pause to solve). Furthermore, they don’t give you the pattern until the end

It would have been helpful to include that each chest has exactly 6 markings. I don’t assume that the animations are 100% accurate

Finally one that I could solve

These riddles have been easy af. None hold a candle to the three gods riddle or even Einstein's riddle.

YES! I ACTUALLY SOLVED THE RIDDLE THIS TIME

What if the Ancient Atlantarctican numeral system is not decimal?

Provided that the ancient people used 10 based number system 😛