Ever play the game Myst? As a kid that's exactly how it was. Days of banging my head and then a rush of finally figuring something out. Really miss that
post
For everyone saying it's the difference between the two numbers, it's not it. Because the last one should be 8 to follow the rule
Figured it out. Weirdly, knowing you solved it made me confident I could too, and I don't even know you 🤔
spoiler
I focused on the anomaly ignoring the rest, tried to see what possible rules could lead to it, then went back to see which rule also applied to the "non-anomalous" numbers.
This is exactly how George Bernard Dantzig proved two previously unproven statistical theorems, when he thought they were homework assignments.
Once I saw a video about Mario Kart speedrunning history and there was a record on Rainbow Road that lasted for years. Than someone broke it but just told the community without showing how it was done. In a couple of days someone else figured it out and did it too. Sometimes we just need to know it is possible
Yes, the hint that the answer was obvious once you knew it was extremely helpful.
I'm not that quick with math, so knowing that the answer was going to be simple helped a lot. Every time I had an idea that was too complicated, I shelved it and kept looking for something that might be simpler.
It also helped that I was a camp counselor, and one of our survival techniques was to have riddles with simple rules that the counselors were able to operate very easily, but which the kids used lots of brain power to try to figure out.
What the heck man I have things to do today.
I wish I saw this first. I'm very prone to off-by-one errors.
I opened the comments thinking that I solved it, then some comments with broken spoiler tags essentially spoiled the actual answer for me, despite my best efforts to ignore them.
With these types of puzzles, I normally start looking for solutions that don't just involve the obvious operations. Had I seen your comment first, I would've continued playing with the first thing I noticed (and later abandoned for the wrong solution) and I think I would've got there by myself eventually.
Either others need to be more mindful of their spoiler tags, or I need to stop using Sync for Lemmy. It's probably the latter; I've seen such weird formatting that only makes sense if I assume Sync's Markdown renderer is broken.
I think I figured it out, but it's so easy that I don't think that could possibly be it. But it is, apparently.
Non-bastardized version:

How do we know if we're right then?
Ah, typo is short for typographical error. I’v never realized that before.
I figured it out took about 10 minutes, thought i was onto it immediately until I had 8 at the end haha
It took me several minutes but I finally got it. The comment saying to focus on the "anomaly" and how it could be 7 helped me to get there.
Yeah, feels pretty silly that I didn't see it sooner. I overcomplicated it haha.
I admit this one extended my toilet time more than I intended, but I got it!
Got it. Very misleading puzzle, haha.
I'm really confused. What was misleading?
I think I figured it out but I always second guess myself lol. I feel like getting it on the first try means I am way off.
Nice puzzle, at first you go "wtf last should be 8" but then I read the last sentence "not a typo" and took some minutes to crack it. If it wasn't for having seen a similar solution in a different puzzle I would have been completely lost and once you know the solution it's impossible to not see it. I can see how the author of the puzzle really liked it.
I have to admit that I believe I have successfully found the solution.
It took me about 2 minutes lol.
Thank you for the share. I will be back in three years time
Wow so easy, I got this in negative 4 second, literally 4 seconds before I even saw the puzzle. Of course I'm not going to share the solution here because I don't want to ruin It, but I definitely got it.
The number of comments in this thread where people confidently declare they solved it with the wrong answer is absolutely baffling. Especially since it literally calls out the exception to that 'solution' in the post itself. Did those people not even look at the 7? That's the real strength of this puzzle, making idiots who think they're geniuses loudly prove their stupidity.
Yeah it takes a different type of self confidence to think someone else can consider "adding two numbers" as their master piece puzzle lol.
I think I've been addled by years of seeing versions of "99% of MIT students get this WRONG! can you do better?" proceeded by 2 + 8 ÷ 4 = ?. I didn't comment but there was some time where I thought I had it and completely missed that the 7 contradicts the pattern, even though it's specifically called out. I'm glad someone did comment so someone else could correct them, otherwise I would have left the puzzle behind never knowing I had gotten it wrong.
Figured it out! That was cool, thanks!
Tap for spoiler
Once I saw it and heard "the solution isn't obvious", I got focused on the idea of digital roots cuz I thought back to the game series 999. But that didn't work, so I focused on the shape of the pizzle and thought it looked like a thermometer, so I tried conversions of F to C, which also didn't work. But when I heard other people say that it made then think about the "obvious" solution and work around the 7, I thought back to my digital root idea and realized I was applying it in a different way in 999 versus what's happening here.
This was a fun adventure~
Took me about 20 minutes. There's a rule you find first that would work if the 7 was an 8. But it isn't. So there's another rule.
until I read your comment I was puzzled as to why anyone would consider something so straightforward a "masterpiece", but yeah, it's quite a clever piece of misleading on the puzzle-setter's part.
Got it in my first try! Thanks for making me feel extra smart today, though I think I'm just lucky. I recently watched a horror game with a similar one xD
I prime factored everything and was looking at ways to manipulate the factors together in a sensible rule. Seemed like a good approach, with the prime numbers at the end.
Now I'm a bit disappointed that
spoiler
it was just the digits and not the factors...
I love puzzles like this—the rule always seems obvious after you see it. It’s satisfying when something that sits in the back of your mind for years finally clicks.
Got it! Really cool puzzle. I used to enjoy solving puzzles like this, but nowadays I don't spend time in that.
Got it. Nice puzzle.
First I figured out what was meant by the number 7 isn't a typo, by jumping to the wrong solution. Next I figured out the next idea was and it worked. No spoilers ༼ᕗຈل͜ຈ༽ᕗ
Well, I got it correct with a guess based on a casual glance at what was there, not how the numbers actually relate or calculations based on rules or patterns.
Then I had to figure out how it actually worked.
Which was harder -- I wish I had kept scrolling.
That was a mean one. Adding another row at the top would expose it, though.
Oh i see,
Its
solution
12
You add up the digits.
(7+2)+(9+9)=9+18=27
9+(4+5)=9+9=18
(1+8)+(3+9)=9+12=21
(2+1)+(3+6)=3+9=12
3+(2+8)=3+10=13
(1+3)+(2+1)=4+3=7
Yay
Plz fix spoiler tags
Looks like this for me?

Moved it down a line is it better?
It didn't help but I appreciate you trying. I think this is the moment I realize Sync is so wildly unsupported that it can't read spoiler tags. Sigh. That's on me.
Being real, if this post hadn't made it clear that the solution was non obvious, I likely would have given up before getting it, just because my chicken is being more interesting than usual.
But, knowing that there was a "trick" to it, meaning that it takes some lateral thinking, I didn't take my usual approach to number puzzles, which means it only took one look at the upper left for the likely solution to be visible. Then it was just running down and testing with the rest, then plugging in for the solution.
No way in hell I would have had the patience for it when my baby bird is being a silly dinosaur without that front loading assumption the solution wouldn't be evident with a systematic approach. Oh, I'd have given it maybe fifteen minutes, but with a fuzzy butt in play, that would have been it
you what? lol
Wow, I just woke up and saved this to have a nice puzzle to work on for a while but I figured it out in like a minute... Kinda disappointed that happened to be honest.
I figured it out in about 3 minutes. I think I'm autistic or something
Same... My brain was hungry for a puzzle to dig into and now its already over. Big sad.
Took me a bit more and I'm not autistic. But: see below.
Hint that helped me
Reading op claiming he figured it by just looking at it and not making complicated calculations on a piece of paper probably helped a lot.
I’m afraid that this post has ruined my evening. I can’t figure it out and can’t let it go. I hate this.
Edit: I would not have survived if my life depended on my answer. I had to read through four to five people talking about methods until I noticed it. I’m really a stupid person.
Took me a few tries until I figured it out. It's cunningly misleading but it's not a trick puzzle (as I had suspected from some people's comments). There is a simple pattern.
I can give one hint if you want.
The solution reminded me of "Numerology". Which I am familiar with and probably why I was able to solve it in about a minute.
Made me remember the extremely simple logic suite, a child could do it, but I had to sleep on it:
O T T F _
What's the letter after F ?
Solved it. Wonderful. I got really hung up on dividing things by nine and seven, trying to use the remainder and stuff. But the answer, as always, is far more obvious. That which we are so used to interpreting, we simply ignore it.
Thank you for posting this, it was exactly what I needed today and I didn't know it!!
I still keep thinking it's 15, which I know is wrong, and then I math in 14,but I can't figure out a function. Does someone want to dm me or spoiler me the function how it works? My brain is too full of more important stuff and I cannot make room for this. But I must know!
Someone else commented the pattern. The answer is not 14 or 15.
Hint
There is no function. You won't find the answer by trying different combinations math operations on the values. You need to think more outside the box.
Hint #2
Ignore the values.
Hint #3
Focus on just three numbers. How can 13 and 21 produce 7?
top 100 comments