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Can You Solve This Problem?

This problem can be solved by pre-school children in 5-10 minutes. By programmers in one hour. By people with a higher education… Well, check it out yourself and post the answer in the comments when you have solved it. Now, those who want to solve it, do not cheat to see if anyone has posted the answer. But then, posting just the answer does not explain the logic here.

This took me just few minutes, so I guess I have a pre-school mentality….

Now, think outside the box, folks. There are a couple links to clues below the problem if you get frustrated, as well as a link to the answer and logic used to solve the problem.

8809 = 6
7111 = 0
2172 = 0
6666 = 4
1111 = 0
3213 = 0
7662 = 2
9313 = 1
0000 = 4
2222 = 0
3333 = 0
5555 = 0
8913 = 3
8096 = 5
7777 = 0
9999 = 4
7756 = 1
6855 = 3
9881 = 5
5531 = 0

2581 = ????

First clue, click here.
Second clue, click here.
Answer and logic, click here.


  1. I, too, lost patience after maybe 5 minutes. I was correctly working on visuals, like how many digits in each line are the same, or counting the occurrences of a certain digit. I’ll never know if the correct answer would have occurred to me.

    • I spent almost 40 minutes trying to figure out this problem and didn’t get! You need more patience! But I did get the answer of 2 becasue you need to count the circles in the numbers.

    • LOL! Thanks… I am positive you do have a highly developed brain. To solve the problem, you just have to look at it form a different perspective. The true meaning of thinking outside the box.

    • You are NOT an idiot! I don’t ever want to hear those words from your computer keyboard ever again! You are a genius!!! Your writing skills are unique and very rare. You have an incredible talent – I wish I just had10% of what you have. So problems like this aren’t your forte… big whoop. Some people see it, some don’t. Doesn’t mean a damn thing towards intelligence.

      Okay, I think I will end my scolding now…. And I’m serious, I never want to hear you type anything like that ever again.

  2. This problem is bollocks.
    I didn’t solve it, and yet I have no trouble solving Mensa problems. I don’t think they mean anything either to be fair.

    • I am a member of Mensa. The problem is valid and has an answer and very logical reasoning. You just have to move out of an adult frame of mind and into a child’s frame of mind. They think more visually at a young age. Pre-schoolers cannot add, and counting is limited. But what can they do? See consistent shapes because that’s what they’ve been doing…. squares, triangles, CIRCLES…

      • You might be correct about moving out to a child’s frame of mind. But not entirely.
        Actually, I discovered the answer by maths and not by visual view.
        I discovered the padron 8=2, 6=1, 9=1 and 0=1 by decoding the value of each number basing myself in the data presented.
        For example, we know 7=0 (because 7777=0), 5=0 (also for 5555=0) and 2=0 (2222=0). Thus, if 7756=1, 6 as to value 1, because 7+7+5+6=1 0+0+0+6=1. We can confirm this in 6666=4 1+1+1+1=4
        And so on, I was able to โ€‹โ€‹found the values in about 5 minutes.
        So I don’t really believe that programmers take 1 hour to discover the pattern, because I’m a portuguese Speech Therapist and found it in 5 minutes ๐Ÿ˜‰

        But still, it was fun! ๐Ÿ™‚

        • glad someone has a mind like mine :P, i used the same math method and got the answer, but still i feel stupid for not noticing the circles

        • (Several years later… ๐Ÿ˜‰ ) Your technique correctly determined that 8’s have a value of 2, just not /why/ 8’s have a value of 2. But the question didn’t ask /why/, just /what/ (as in, /what/ is the answer). So, nice job! ๐Ÿ˜€

  3. It’s actually a math problem. You just need to consider the series as a bunch of signifiers rather than as numbers proper.
    From the series that add up to 0, we can figure out that 3,5,7,2 and 1 are equal to 0. (5555= 0, 1111=0 etc)
    From the series that add up to 1, we realize that 6,0 and 9 are equal to 1. (6666 = 4, 9999 = 4, 0000=4)
    Then from the single = 6 series, we realize that 8 = 2. (8809 = x+x +1+1 = 6; x = 2)
    With this, we know that 2 = 0, 5 = 0, 8 = 2, 1 =0. 2581 = 0+0+2+0 = 2

    • You are correct but have grossly over worked this problem – made it much more difficult than necessary. You simply assigned a 0, 1 or 2 to the numbers according to the number of closed loops in them.

      For numbers which equal 0 (3,5,7,2 and 1 are equal to 0), that is because those numbers do not have any closed loops. Therefore, 0 loops.

      For “6,0 and 9 are equal to 1” that is because each of those numbers has one closed loop. Therefore, 1 loop.

      For “we realize that 8 = 2” that is because 8 has two closed loops. Therefore 2 loops.

      A pre-schooler is not able to make the connection you did. Plus, your connection was unnecessary. But good job and making it making it work mathematically, but it is the exact same theory as visually counting the closed loops in the numbers. So, in essence, it is not necessary a math problem unless you want it to be a math problem.

      It’s kind of like going from Paris to London. You can go directly, or go via way of Moscow. You got to your destination, but took the Moscow route.

      • But honestly, that’s exactly how I solved it as well – maybe “simpler” if you don’t think about the visual shape.

        • It’s impressive how you did that. And is exactly right. Just so we arrive at the destination. As a Mensan, I often over-complicate things. I am actually horrible with multiple choice questions because somehow in my mind, I can make several answers work. I just made myself focus on thinking like a child and got this one quickly because of that. Otherwise I would have taken much longer and probably came up with your system.

    • yep that’s me too… but really Moscow is lovely, I don’t see why not go through it on the way from London to Paris it’s much more fun, espaicaly if you’re not a pre- schooler ๐Ÿ™‚

  4. V nice. Confess I clicked to find the answer.

    Dont know how I missed getting notifications of these posts.

  5. I gave 0,6,9 the value 1 and 8 the value 2 it took me about 10 minutes to solve the last problem but just to count the holes ๐Ÿ˜€ who would think of that

  6. I got 2 as the answer but I didn’t get it using this “closed loop” method. It was simply finding out how much each number was worth. Example”2172=0″ you now know that 2, 1, 7 all have values of 0. That makes sense right? lol

  7. LOL! I often fail at exams for being too excited and not read directions. hate my self for not doing it till now until i read the first clue. the answer is 2. XD

  8. that’s not how I solved it at all, although I see how many would go that route.

    I started by isolating 0’s… 5555=0 so 5 must =0. 2222=0 so 2 must equal 0. 1111=0 so 1=0.

    To get the 8 i saw 0000=4 so 0=1, 9999=4 so 9=1, so 8809=6 with 09=2 means 8 = 2.


    Which means 2581 = 2.

  9. All the discussion about how you arrive at the answer doesn’t address the fact that the question is B.S. It’s a false premise designed to make you feel foolish. Those that “solved” the problem mathematically didn’t overthink it. They came up with a reasonable solution that fit within the framework of the question, exposing how incorrect the initial statement is. Apparently, the educated were supposed to take forever to figure it out and give up, but the mathematically inclined worked it as a math problem and came up with the “correct” solution just as quickly as the imaginary pre-schoolers would have. The fact is, pre-schoolers may have come up with the “correct” answer by chance, but I believe the assessment of how long they would spend with it is basically accurate. After looking at the seemingly senseless array, they would shrug and move on to something more interesting. Pre-schooler don’t, regardless of what this question would ask you to believe, see numbers in terms of closed loops. They are more likely to be overwhelmed by 4 digit numbers and not even attempt to figure out the answer.

  10. There is another way to get to the solution.
    Let’s ignore the series of four numbers on the left and just work with the single digit numbers on the right. If we start adding from top to bottom, we have series that add up to 10. Once you reach 10, you move to the next secuence. For instance: 6+0+0+4=10. Then 0+0+2+1+4+0+0+0+3=10. Then 5+0+4+1=10. And finally 3+5+0+x=10. Therefore x=2.

    • If we start adding from top to bottom, we have series that add up to 10. Once you reach 10, you move to the next secuence. For instance: 6+0+0+4=10. Then 0+0+2+1+4+0+0+0+3=10. Then 5+0+4+1=10. And finally 3+5+0+x=10. Therefore x=2.

      That’s good, but coincidental. For example, if you switch the placement of the two numbers:

      8913 = 3
      8096 = 5


      8096 = 5
      8913 = 3

      Then it will not work because you will then have:


      Great creativity, though. Thinking outside the box is the only way to get anywhere.

      • i used that way too…adding all the numbers like that and i somehow think the answer would be 2 to make it 10.I guess I’m just lucky. I would never dream to count the loops.

    • (Several years later… ๐Ÿ˜‰ ) I think it is both coincidental, and lucky, that “2” is the right answer. Why is it required that this is the last number in the series? Couldn’t this answer have been a “0” or a “1” just as easily, with more numbers after it? Okay, well it /was/ the last number given; so, both lucky and coincidental, I think. ๐Ÿ˜‰

  11. I had to look at the first clue, about thinking like a pre-schooler, and then the answer just came to me……

  12. I hate to throw a spanner in the works here, but what about the number 4? The puzzle doesn’t use a 4 in any of it’s numbers. Are we counting “circles” within the numbers – OR – are we counting “enclosed spaces” within the numbers?

    4 – As written on a computer, DOES include an enclosed space. Therefore it would be “1”.

    4 – However does NOT contain a circle. So it would be a “0”.

    So here’s the next number for you in the pattern::

    4800 – ??

    Could be 4 OR 5…

      • I think the number 4 was left out of this puzzle by the creator on purpose for this very reason…! Causes further brain scratching…!

        • It’s still a damn good problem. Especially because it also shows how we, as humans – especially higher educated people – need to step outside our box and go back to the “basics.” We tend to over complicate our lives all the time, every day. I love this problem specifically for that reason. And it’s funny… so many people have tried to poo-poo the easy (and correct) answer by working out all these calculations, etc. “It has to be more difficult than that.” More so because they’re pissed because they probably didn’t figure it out, yet most kids can figure it out in a few minutes. That was the key right there. And I’m lucky I caught that right away otherwise I probably would have tried to right a damn program to figure it out.

  13. well I got the answer but through “analyzing” the… equations (I added the numbers in each of them to see the new “value” they were given…) not through the more simple way of just looking at them. took between 5 to 10 minutes. it was fun though ๐Ÿ™‚

  14. further explanation: 1+1+1+1=o… 1=0 it was the same for the numbers 2,3,5, and 7. but, 0+0+0+0=4 so 0=1 and that’s the same for 6 and 9. I than put the new values where 8 has been for example 8+0+9+6=5 would be 8+1+1+1=5 so 8=5-3, 8+2. 4 wasn’t needed and 2+5+8+1=0+0+2+0 =2.

  15. I did the same. Seems less arbitrary than looking at shapes, but that’s just me. Proves you are not necessarily wrong to think “inside” the box…

  16. I figured this out, but i never made the connection to closed loops. i just figured out that 8 was worth 2, and 6,0,9 were worth 1.

  17. Civil Engineer – took me 10 minutes… to look at the answer. couldnt figure it out. I think it would be more fun if you put the part about the preschoolers answering it more quickly under the first clue. i would have spent more time working on it.

  18. Hey , I am programmer and come up with the almost same solution as “uguu”…
    So I spotted that 0 =1 , 1 = 0, 2=0 , 3 = 0 ,4 = ? , 5 =0 , 6 =1, 7= 0, 8 =? , 9=1 after looking on the “same number” series (1111,2222….), then I took 8809 = 6 , so 0 = 1 and 9 = 1 so 8 must be 2 ๐Ÿ™‚
    do you think that the fact of being programmer made me think like that ?:) (well it took me no more than 30 minutes anyway:)) was trying to think as pre school child but forgot what pre school child thinks (I am 30 and my child has only 2 months :)) do you thin that age does matter ?

    Any way it was good one !! Thanks for that !!

  19. Just had to think like a pre-schooler and throw out my degree in mathematics. Took about 15 seconds to do that, and it felt good ๐Ÿ™‚

    • Oh, and the actual “first clue” and most important clue is that pre-schoolers can do it easily. *That*’s the metadata you gave us that leads straight to the answer.

  20. I started, went back to the instruction to think outside the box and had it in about 15 seconds (plus another 15 to check the other samples). Sorry.

  21. I may have been lucky but looking at the answers and ignoring the zeros there appeared to be a pattern that alternated in the answers. 4 plus 2 is 6. 4 minus 3 is 1. 4+1 is 5. 5 minus x is 3. x is 2. Five minutes.

    2 4+2=6
    3 4-3=1
    1 4+1=5
    0 5-x=3; x=2

  22. This problem is one big mind trick. The way it is formulated and if you use โ€œ+โ€ and โ€œ=โ€ as we know them from mathematics the real answer is not just only 2 but 0(zero) also and 1 also and 6 also and so onโ€ฆ because:
    0000 = 4 means 0+0+0+0=4 means 0=1
    2222 = 0 means 2+2+2+2=0 means 2=0 so then 2=1=0
    But also the problem says:
    6666 = 4 meaning 6=1 then 2=1=0=6 and so on.

    You cannot use some sing as being a value and a sign that has a different value in the same time because that is not logic at all. 2 cannot be 0 and 2 in the same time knowing that 0 is different than 2.
    It looks logic but it is not.
    The solution with counting the circles gives more logic than the other one.
    In order for this problem to be logic then in the left of the โ€œ=โ€ sign should be something else than numbers used as signs.

    • you are over thinking things here, in programming, we can declare a variable, that variable can be any combination of letters or numbers, and we assign those specific combinations of letters and numbers a value. normally we can’t use a number as a variable in programming for obvious reasons, however, in theory, we can. Using this programming logic as our guideline, everything to the left of an = sign is a variable, and everything to the right, the sum of those variables.

      if working with that many numbers confuses you, replace the numbers on the left of the = sign with letters, and it should make more sense.

  23. I took it real easy so as not to strain my brain. With time the answer just appeared on the screen. Phillip

  24. Once we are grown, we look at numbers and letters as conveying abstract information (quantities, sounds). Admittedly, I did look at all the hints and eventually the answer. When I did though, I couldn’t help but laugh. I’m pretty good with patterns, but I would never have thought to look at the figure eight for what it is (two loops) or to look at a zero as one loop. It’s amazing how much our way of looking at things changes as we get older, especially with regards to symbols which we are taught to simply extract information from, rather consider the symbols themselves.

  25. I got this one using math, didn’t think of the closed loops things though. as soon as I saw so many numbers cropping up, and the mention of programmers, it got me to thinking of variables, and how they hold value, so I wrote a list ranging from 0 to 9, with equals signs, and started filling in the values based off the alple evidence provided, and had it solved in less than 2 minutes :).

  26. I was thinking modular arithmetic and all this other weird stuff cause I’m in a group theory class right now. Then I read the second hint which said it wasn’t a math problem and sighed.

    Then I got it 10 seconds later ๐Ÿ™‚

  27. Haha…I was thinking of my nieces and picked up a cell phone since they like playing with their mom’s iPad. And I over thinked it. But the top left numbers all equal zero (1,2,3,4,5,7) then like the rest. found the values for 6,8, 9, 0. Haha loops…wish i could be a kid again. Have a great day!

  28. Surprise! I got it in 30 seconds or less I would say. The answer is two. I don’t know if anyone else agrees with me. Perhaps it is because I have had several strokes.

  29. I got two, but for a different reason. I obviously over thought it, but here:
    Since 0000, 6666, and 9999 are all equal to 4, each individual number (0,6, and 9) is equal to one. 4 and 8 are both equal to 2. If you look at the first one, 8809=6, you’ll see that 8 = 2, 8 = 2, 0 = 1, and 9 = 1. I’m pretty sure that this key works for all of them.

  30. Would never have gotten there ๐Ÿ˜‰ . Even after reading the answer it took me about 5 minutes. Tried all kinds of stuff I know about series/sequences. After the answer said it is about counting the circles … well I tried to transform the numbers so that they would represent a circle xD.
    Nice problem though.

  31. Problem gives you that 1,2,3,5,7 all = 0 —- and 0,6,9 all =1

    So if 8809=6 and 0 and 9 are 1 each, that’s 2+2+1+1
    2581 = 0+0+2+0 = 2

  32. I actually solved this with a completely different logic, as a math problem. It never occurred to me that it was about the closed loops, and yet my logic was correct and lead me to the correct answer..

  33. learned years ago that if u can’t get the answer u r simply looking at the wrong way. after about 2 mins of looking at it in a few different ways i looked at it as shapes and boom went da dynamite!

  34. Took me 3 minutes, I didn’t do it by the number of loops though. I saw that certain sets = certain amounts. For example, 0000 = 4. I reasoned that 0 = 1. So, I knew I needed to know the values of 1,2,5 and 8. I used the same method to reason the values of 1,2, and 5 were 0. Then, I decided that 8 = 2 because 8809 = 6, while 0=1 and 9=1, and 88=4. Therefore 8 = 2 and 2581 = 2.

  35. I just figured out which numbers were assigned a numerical value, didn’t think visually, I thought in the sense of code breaking. Through deduction it was pretty easy to figure out 0 = 1, 9 = 1, 8 = 2 and 6 = 1.

  36. This answer can be figured out by process of elimination as well. Understanding the values of each number allows one to deduce that 8 = 2 and that 2, 5, & 1 = 0. (More than 1 way to skin a cat!) ๐Ÿ™‚

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