# Evil math problem **URL:** \ **Category:** Factual Questions\ **Created:** [September 4, 2011, 4:36pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170 "2011-09-04T16:36:59Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Florida\_Orange\_Juice](https://avatars.discourse-cdn.com/v4/letter/f/94ad74/32.png) [@Florida\_Orange\_Juice](https://boards.straightdope.com/u/Florida_Orange_Juice)\ **Post date:** [September 4, 2011, 4:36pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/1 "2011-09-04T16:36:59Z")
–12-- –73– 6----5 –17– –30– 2----5 –23– – **?** – 4----7 How do 12, 6 and 5 relate to 73? You must figure out some kind of pattern in order to find the missing value. I’ve spent hours and hours and hours. I must be missing something obvious because I have used every combination of add, subtract, multiply, divide, square, and cube. I’ve found a whole bunch that yield 73. For example, 6^2 + 5^2 + 12 = 73. But that doesn’t work for the next triangle! I’ve tried counting individual digits. I noticed that 1+2+6+5 = 14, 1+7+2+5 = 15, and 2+3+4+7 = 16. That probably means nothing. I don’t know. You see, this problem is imprinted in my mind. I need a solution now or I’m going to go insane. ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [September 4, 2011, 4:49pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/2 "2011-09-04T16:49:15Z")
Do you have a source for this? Are you sure there’s no typo in what you’re working with? ---
**Author:** ![Florida\_Orange\_Juice](https://avatars.discourse-cdn.com/v4/letter/f/94ad74/32.png) [@Florida\_Orange\_Juice](https://boards.straightdope.com/u/Florida_Orange_Juice)\ **Post date:** [September 4, 2011, 4:55pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/3 "2011-09-04T16:55:14Z")
This is correct as far as I know. I don’t have a source, however. ---
**Author:** ![Wendell\_Wagner](https://avatars.discourse-cdn.com/v4/letter/w/8491ac/32.png) [@Wendell\_Wagner](https://boards.straightdope.com/u/Wendell_Wagner)\ **Post date:** [September 4, 2011, 5:27pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/4 "2011-09-04T17:27:36Z")
What does this problem even mean? Is the - supposed to stand for the same digit in every place where it appears on all nine lines? Does it stand for a single digit in the top three lines, another digit in the second three lines, and and a third digit in the third three lines? Or does this mean something else entirely? Unless we know that, we can’t answer the question. ---
**Author:** ![Florida\_Orange\_Juice](https://avatars.discourse-cdn.com/v4/letter/f/94ad74/32.png) [@Florida\_Orange\_Juice](https://boards.straightdope.com/u/Florida_Orange_Juice)\ **Post date:** [September 4, 2011, 5:37pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/5 "2011-09-04T17:37:47Z")
Sorry, the dashes don’t mean anything. The numbers are supposed to be arranged in a triangle, with 73 in the center and 12, 6, 5 at each corner. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [September 4, 2011, 5:40pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/6 "2011-09-04T17:40:25Z")
> [@](#): > > This is correct as far as I know. I don’t have a source, however. Wait, what? So it just appeared in your brain having been beamed there by aliens? How could you “not have a source”? ---
**Author:** ![Alan\_Smithee](https://avatars.discourse-cdn.com/v4/letter/a/2acd7d/32.png) [@Alan\_Smithee](https://boards.straightdope.com/u/Alan_Smithee)\ **Post date:** [September 4, 2011, 5:41pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/7 "2011-09-04T17:41:40Z")
What do you mean you don’t have a source? You just made it up yourself? ---
**Author:** ![Fiendish\_Astronaut](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fiendish_astronaut/32/3295_2.png) [@Fiendish\_Astronaut](https://boards.straightdope.com/u/Fiendish_Astronaut)\ **Post date:** [September 4, 2011, 5:44pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/8 "2011-09-04T17:44:19Z")
1. I don’t have a source for my answer however. ---
**Author:** ![Bagistan](https://avatars.discourse-cdn.com/v4/letter/b/ea5d25/32.png) [@Bagistan](https://boards.straightdope.com/u/Bagistan)\ **Post date:** [September 4, 2011, 5:49pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/9 "2011-09-04T17:49:29Z")
Here is one solution, but probably not the intended one: Labeling the individual digits like this… –AX– –BY– C----Z …we can construct these equations that holds for the first two triangles: B=A+C Y=C-|Z-X| From this we can complete the third triangle: –23– –60– 4----7 ---
**Author:** ![smiling\_bandit](https://avatars.discourse-cdn.com/v4/letter/s/e9a140/32.png) [@smiling\_bandit](https://boards.straightdope.com/u/smiling_bandit)\ **Post date:** [September 4, 2011, 6:34pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/10 "2011-09-04T18:34:41Z")
This is the reason I hate riddles and “loguic” puzzles. They’re usually less about reasoning or logic, or even word games, than figuring out whatever the creator was thinking. ---
**Author:** ![Florida\_Orange\_Juice](https://avatars.discourse-cdn.com/v4/letter/f/94ad74/32.png) [@Florida\_Orange\_Juice](https://boards.straightdope.com/u/Florida_Orange_Juice)\ **Post date:** [September 4, 2011, 6:36pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/11 "2011-09-04T18:36:53Z")
Okay, I do have a source, but you can’t access it, so what does it matter? ---
**Author:** ![hajario](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hajario/32/171_2.png) [@hajario](https://boards.straightdope.com/u/hajario)\ **Post date:** [September 4, 2011, 6:41pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/12 "2011-09-04T18:41:34Z")
> [@Florida\_Orange\_Juice](#): > > Okay, I do have a source, but you can’t access it, so what does it matter? It could help us to solve it. You never know. It’s ok to say, “an email from a friend” or something. ---
**Author:** ![Florida\_Orange\_Juice](https://avatars.discourse-cdn.com/v4/letter/f/94ad74/32.png) [@Florida\_Orange\_Juice](https://boards.straightdope.com/u/Florida_Orange_Juice)\ **Post date:** [September 4, 2011, 7:59pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/13 "2011-09-04T19:59:39Z")
Thanks for the responses (I also got 64 as one of my answers, Fiendish Astronaut). But I have an unfortunate announcement to make. I just received word from my source that the second “triangle” is 17, 2, 3, NOT 17, 2, 5. And that makes all the difference… ---
**Author:** ![Wendell\_Wagner](https://avatars.discourse-cdn.com/v4/letter/w/8491ac/32.png) [@Wendell\_Wagner](https://boards.straightdope.com/u/Wendell_Wagner)\ **Post date:** [September 4, 2011, 8:05pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/14 "2011-09-04T20:05:04Z")
Oh, come on. At least make some attempt in your OP when you ask a question like this to explain what the problem means. It was not remotely clear that –12– –73– 6----5 means a triangle with 12, 6, and 5 at the corners and 73 in the middle. We’re not psychic. ---
**Author:** ![Florida\_Orange\_Juice](https://avatars.discourse-cdn.com/v4/letter/f/94ad74/32.png) [@Florida\_Orange\_Juice](https://boards.straightdope.com/u/Florida_Orange_Juice)\ **Post date:** [September 4, 2011, 8:14pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/15 "2011-09-04T20:14:40Z")
It doesn’t really matter what the shape is. The key is that 12, 6, and 5 are manipulated in such a way as to yield the number 73, which I mentioned in the OP. But, yes, it’s much easier to visualize in triangle format. Sorry for the confusion. ---
**Author:** ![Alan\_Smithee](https://avatars.discourse-cdn.com/v4/letter/a/2acd7d/32.png) [@Alan\_Smithee](https://boards.straightdope.com/u/Alan_Smithee)\ **Post date:** [September 4, 2011, 8:23pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/16 "2011-09-04T20:23:00Z")
> [@Florida\_Orange\_Juice](#): > > It doesn’t really matter what the shape is. The key is that 12, 6, and 5 are manipulated in such a way as to yield the number 73, which I mentioned in the OP. But, yes, it’s much easier to visualize in triangle format. Sorry for the confusion. That was impossible to tell from what you gave us. I thought the numbers were in columns with the dashes representing spaces in the columns. Imagine if I then went and posted it on another website or wrote it out and gave it to someone to solve, using my interpretation of what it was supposed to be. We get a lot of puzzles posted on this board, and I don’t think I’ve _ever_ seen one that was actually solvable as it was first presented. There’s ALWAYS something that the person posting misheard or couldn’t reproduce or though wasn’t important. It turns into a game of Telephone instead of a puzzle. THAT’S why it’s important to know the source. Until we figure out whether you misheard, misread, or misinterpreted something, we can’t tell you why you can’t solve it. And until we know what the original problem was in its original format and original context, we can’t solve it either. ---
**Author:** ![Florida\_Orange\_Juice](https://avatars.discourse-cdn.com/v4/letter/f/94ad74/32.png) [@Florida\_Orange\_Juice](https://boards.straightdope.com/u/Florida_Orange_Juice)\ **Post date:** [September 4, 2011, 8:31pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/17 "2011-09-04T20:31:11Z")
Understood ---
**Author:** ![Jamaika\_a\_jamaikaiake](https://avatars.discourse-cdn.com/v4/letter/j/7993a0/32.png) [@Jamaika\_a\_jamaikaiake](https://boards.straightdope.com/u/Jamaika_a_jamaikaiake)\ **Post date:** [September 4, 2011, 8:37pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/18 "2011-09-04T20:37:12Z")
> [@Alan\_Smithee](#): > > That was impossible to tell from what you gave us. I thought the numbers were in columns with the dashes representing spaces in the columns. Imagine if I then went and posted it on another website or wrote it out and gave it to someone to solve, using my interpretation of what it was supposed to be. Seriously! I thought it was 3 5-digit numbers with the dashes representing missing digits. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [September 4, 2011, 9:15pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/19 "2011-09-04T21:15:06Z")
FWIW, I thought the numbers were supposed to be arranged in triangles, with the corner numbers relating to the middle numbers. It seemed obvious to me. (Not that I got the answer.) ```auto 12 / \ / 73 \ / \ 6--------5 17 / \ / 30 \ / \ 2--------5 23 / \ / ?? \ / \ 4--------7 ``` ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [September 4, 2011, 9:19pm UTC](https://boards.straightdope.com/t/evil-math-problem/595170/20 "2011-09-04T21:19:35Z")
> [@florida orange juice](#): > > for example, 6^2 + 5^2 + 12 = 73. 2^2 + 3^2 + 17 = 30. ETA: So 4^2 + 7^2 + 23 = 88 is the answer. [Next page](https://boards.straightdope.com/t/evil-math-problem/595170.md?page=2)