Very complicated math

[ict]

Hey guys I wanted to share something with ya all related to maths. It's a very weird and difficult me and my friends tried to solve it and it drove us crazy because we just couldn't come to a result. The question is actually out of some sort of ''exam'' and is supposed to be solved by being ''logical'' lol. So heres where you guys come into play :D. It would be great if some of you are possibly able to respond this question and not only the right answer I would love the explanation behind it, too.

So yeah enough talking I'll just drop it now:

It says ''remplacer logiquement'' which means to replace logically, basically they are asking which digits would fit into the (?) space out of those options a, b, c, d, e.

So yeah good luck guys hope to get answers. :o

 

[Blitz]

My friend Sigilyph decided to give it a shot. Here's his explanation:

"Ok so for me the reason why I got 67 is because there is not just one sequence in this puzzle, but 3.

To me I saw a flipped sequence in the middle, like the numbers on one side were in backwards order on the other side. So like 76 on one side was 67 on the other, 49 was 94.I found this out by ruling out the other sequences, which are as follows:

Exclude the number 58 at the end for this, since its not part of this sequence.
Place your cursor between the numbers 78 and 56, and pretend it is a mirror and a middle section of the sequence.

Following this mirror between 78 and 56, the numbers ascend in the pattern 12345678, alternating on either side of the mirror starting 2 places out and going inwards.
Theres 12 on the right two places in, 34 opposite of it two places in, 56 on the right again 1 place in, and then 78 opposite it on the left one place in. Its in ascending order alternating between the left and the right of the center of the sequence.

This means that the whole thing is not just one sequence of numbers since the pattern ends there. There are 2 entirely different logical patterns here.

If you notice, 49, 58, and option A (67), are decreasing in distance of numbers away from each other. this is another pattern because on the left side 76 and 94 are the doing the same thing, except this time they are getting closer together in jumps of 2 instead of 1.

67 is the only number to fit this criteria and by eliminating one of the sequences (the irrelevant middle section) it becomes easier to see the resulting patterns on the outside (the flipping of the numbers via “mirror” and the degrees of separation pattern)

This probably makes 0 sense but it did to me."

 

[billymills]

which clique is liking this thread?

 

[vonFiedler]

which clique is liking this thread?

I would guess that people are talking about it on irc and are actually interested in the problem.

Mind those posting, this is an op asking for answers, not open-mic night.

 

[UncleSam]

Oh it's probably 84 btw

The numbers on the ends can be added or multiplied to make 13, and the fourth number can have it's digits multiplied together to make it's corresponding right-hand side number, 56. Therefore, the digits of the missing number must combine together to make 12 in some way.

Not a perfect pattern but the fact that so many of the numbers either add or multiply to give each other or equivalent results means that there is some desired pattern with multiplying/adding the digits of each number. No way it's just a coincidence.

Also von hates fun :(

 

[ict]

This theory seems interesting but imo its way too much complex thinking for a simple logical question, I definetely see what you were attempting to do but eh I dont really think theres that much behind it actually that you would need to imagine that some numbers aren't there and the stuff with mirroring doesn't seem that logical, more like super exaggerating in possible way D:

 

[UncleSam]

Basically I see three groups here:

Group 1: 56/78 (numbers in the 4th and 5th positions): These numbers either multiply to or are 56
Group 2: 76/94/49/58 (numbers in the 1st, 2nd, 8th, and 9th positions): these numbers all add to 13
Group 3: 34/12 (numbers in the 3rd and 6th positions): these numbers either multiply to or are 12

Not sure whether there's any sort of symmetric perfect pattern here but the fact that all the answers add to either 11, 12, 13, or 7 (like 34) means that this is definitely the right general approach to viewing these numbers, imo

 

[bluri]

%Bluri: 76 34 56 12 ?
%Bluri: wäre die erste Zahlenreihe
%Bluri: immer sind die Ziffern X und Y+/-1
%Bluri: aber wie krieg ich X raus
%Bluri: 7 3 5
%Bluri: -4 +2 -4 vllt
%Bluri: passt net
%Bluri: ahh
%Bluri: 12 34 56 78
+Lord Esche: die 49 fuckt mich ab
Klaas N Raum: +22
%Bluri: nee
%Bluri: es is auf jeden fall
%Bluri: c
Icey Tea: nein
%Bluri: yn
%Bluri: fick dich
%Bluri: nein man es is
Icey Tea: ok
%Bluri: a oder b
%Bluri: wegen Zahlenreihe
Icey Tea: ja
Icey Tea: es ist a
Icey Tea: aber warum ist es a
%Bluri: nicht sagen wieso
Icey Tea: ja
Icey Tea: dass weiß ich selber nicht
Icey Tea: lol
%Bluri: 76 34 56 war die Zahlenreihe die ich hatte
%Bluri: 34 56 ergibt sinn
%Bluri: aber wieso dann dieser bruch 76
%Bluri: statt 78 kommt da 67
%Bluri: ehh
%Bluri: 76
%Bluri: also 67 hin
%Bluri: 76 nur vertauscht
%Bluri: 94 78 12 49 wäre die andere Zahlenreihe
%Bluri: jz
%Bluri: hab ichs
%Bluri: 76 94 34 78 56 12 ? 49 58
%Bluri: das is gesplittet
%Bluri: In einen Kern
%Bluri: und ein Rahmen
%Bluri: 76 94 [34 78 56 12] ? 49 58
%Bluri: Der Teil drinnen ist einfach
%Bluri: rechts links rechts link
%Bluri: 12 34 56 78
%Bluri: Und der Rahmen
%Bluri: Bildet Pärchen
%Bluri: 94 und 49 bilnden Pärchen
%Bluri: 76 und für das Frageueichen 67 ist das dazugehärige Pärchen
%Bluri: Zahlendreher halt
%Bluri: und die 58 ist zur Verwirrung da
+Lord Esche: lol
%leru: lol
%Bluri: neben der 76 würde noch eine 85 stehen
%Bluri: aber das zeigen die nicht
%Bluri: yn


Fick dich meine Erklärung ist doch richtig

> glaubt mir nicht

 

[Kink]

I can only tell you what it isn't, 94 and 56.

 

[ict]

Yeah so far we came to the conclusion that its either 67 or 84.

 

[Bughouse]

This is an absolutely terrible question and the testmaker should feel bad.

For the record, you can generally look things like this up on https://oeis.org/

...but this is random nonsense https://oeis.org/search?q=76,94,34,78,56,12

 

[Kink]

Yeah so far we came to the conclusion that its either 67 or 84.

I have no idea about that to be honest, the only discernible integral pattern is a lack of repeated integers. That is the only one-sided condition. Every other nuance strikes me as a bi-conditional pattern.

 

[Style_Dota]

It is not an integral pattern, it's probably some specific functional map that maps certain numbers to one another. Here's an example reference
http://www.projet22.com/sciences/mathematiques-et-logique/article/les-relations-mathematiques-du

ill probably fiddle with this a bit more and see what I get.

Edit: In case this point is interesting, when the value in the ten's digit is "higher" the succeeding number decreases. When the one digit is higher, the number increases. I highly doubt that matters since all of the numbers succeeding 12 are higher but there might be a loop effect.

 

[Uselesscrab]

http://www.pharmandcie.fr/wp-content/uploads/2014/06/Le-Princeps-3.pdf
Found the source and the answer:

spoiler

Question 13 : réponse a) 67

La somme des chiffres dans la ligne verticale donne 13 (7 + 6 = 9 + 4 = 13 etc.) donc éliminer « b » , « c » et « e ». Dans la ligne horizontale les chiffres se suivent 3,4 puis 7,8 etc. d’où a.

 

[Stallion]

This looks like one of those questions that when the answer is presented, it'll look so simple that you'll probably feel like crying.

Edit: I was right.

 

[ict]

Yeah we found out about that source, too ngl it still doesn't convince me lol. Ok its right that the 2 left digits and the 2 right digits sum is 13 and thus eliminates the possibillities of 56 94 and 25. But I don't get what theyre trying to say with a horizontal and a vertical line, i mean is pretty clear theres only a vertical line (correct me if im retarded or something lol). Its trying to say that the 5 middle digits are consecutive numbers so therefore 12 34 56 78. But I really fail to see how a 67 fits in there lol it would be 1234566778 then which makes barely any sense, right?

E: I also fail to see how the 67 has a connection with the 2 left and 2 right digits. Then it would be 2 on one side and 3 on the other side where the sum is 13, fine but where is a pattern there?

 

[Bughouse]

That is such an unsatisfying answer.

Some numbers sum to 13, some others have a difference between their two digits of 1. Therefore 67? That's not ultimately persuasive whatsoever.

Why does it change there? The first, second, second to last, and last numbers all have their digits sum to 13. The third, fourth, fifth, and sixth numbers all have an inner difference of 1. Predict something about the seventh number based on this?

For fuck's sake this explains a lot about the French international students I went to college with, if this is what they consider rigorous math education.

 

[Stallion]

Yeah we found out about that source, too ngl it still doesn't convince me lol. Ok its right that the 2 left digits and the 2 right digits sum is 13 and thus eliminates the possibillities of 56 94 and 25. But I don't get what theyre trying to say with a horizontal and a vertical line, i mean is pretty clear theres only a vertical line (correct me if im retarded or something lol). Its trying to say that the 5 middle digits are consecutive numbers so therefore 12 34 56 78. But I really fail to see how a 67 fits in there lol it would be 1234566778 then which makes barely any sense, right?

That's what put me off that conclusion too

 

[ict]

Oh yeah btw me and my friends had a theory ongoing that the formating might be wrong o.o!
Because it says something about horizontal lines like mentioned before so I would take that into consideration maybe.

 

[Klang]

After trying to solve it for like 20 minutes that ridiculous answer kind of annoyed me tbh.

 

[Style_Dota]

Rofl its actually illogical. There's missing information. That logic would make sense if the question mark answer was 12 and 12 was non existent

 

[ict]

Yeah and ironically it says to replace logically.

 

[Jayde]

Multiple patterns make partial sense if you group [34 78 56 12] and/or [76 94 49 58], but the only one I found that attempts to tie everything together is this: excluding 94 and 34, the absolute values of the differences between the first digits and the second digits of adjacent numbers are always equal. For example, |7-9| = |6-4| = 2, and this works for every adjacent pair except 94 and 34 (I use absolute values because I don't see value in any pattern involving signs). The only choice that satisfies this rule with both 12 and 49 is 67. I still can't make sense of 94 and 34 in this context, but it might be worth noting that when you flip all the numbers (i.e. 76 becomes 67) and the absolute values of the differences of adjacent numbers are the same as before you flipped them (this last part follows automatically from what I established to start the paragraph), the absolute value of the difference between the 2nd and 3rd number is also flipped (60 to 6).

If the answer wasn't what you just said, I would've thought this line of logic had me a couple steps/corrections from the right answer, and I still feel like my answer is better than the source's. You clearly baited the shit out of me by saying this was complicated.

 

[Kink]

Yeah, this is a stupid question. Every other component of the questions is bi-conditional... hence the stupidity of the question itself. Multiple choice is supposed to reflect the "best" answer, but all I see here are bi-conditional answers with no direct derivation to the logic itself.

 

[ict]

Right now I think that most answers given here made more sense than the one this shitty source gave us.. The thing with the numbers flipping was actually my first consideration. While I agree with most of what you've said I dont excluding 94 and 34 makes any sense tbh oo