Lsteral Thinking XIII

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Holmes
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Lsteral Thinking XIII

Postby Holmes » March 18th, 2009, 8:25 am

Lateral Thinking XIII is called "The Missing Number"

Your task is to find the missing number.

Here it is,


     54           (117)           36
     72           (154)           28
     39           (513)           42
     18           (  ?  )           71             
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Sayumi
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Re: Lsteral Thinking XIII

Postby Sayumi » March 18th, 2009, 9:04 am

I'm kinda busy with tests and assignments at the moment, but I couldn't stop myself  ;D
[spoiler]add up the outer and inner numbers
54 (117) 36
5+6=11
4+3=7

same with:
72  28
7+8=15
2+2=4
154

and
39  42
3+2=5
9+4=13
513


so
18  71
1+1=2
8+7=15
215[/spoiler]
"It is one of those instances where the reasoner can produce an effect which seems remarkable to his neighbor, because the latter has missed the one little point which is the basis of the deduction."
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Re: Lsteral Thinking XIII

Postby Holmes » March 18th, 2009, 7:45 pm

Nice one Sayumi! Well, as expected  ;D

Oh, and btw, good luck with your exams and assingments.  :D
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ayw

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Re: Lsteral Thinking XIII

Postby ayw » March 21st, 2009, 11:04 am

I needed quite a while to figure this one out... my LT thinking is getting rusty   :-\    Thanks for continuing to post these riddles, Holmes!

Here are two more to keep the water boiling...
[tt]53   (73)   21
36   (45)   72     
94   (68)   78
15   (??)   67[/tt]
4678   (74)   3419
3224   (39)   8962
1572   (21)   6421
9839   (??)   3031
   

Edit - hints:
····································
A little hint for the upper one
Notice how the outer two numbers are always either both odd or both even.


And a little hint for the lower one
No arithmetic is required for this one  ;)
Last edited by ayw on March 22nd, 2009, 8:42 am, edited 1 time in total.
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Sayumi
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Re: Lsteral Thinking XIII

Postby Sayumi » March 22nd, 2009, 4:24 pm

Finally figured out the first one-took me ages... I had already noticed what you mentioned in your hint, I just didn't realise that it's significant...(can't believe it took me so long-it wasn't that hard!)

Here I go:
(53+21):2= 37 -> 73
(36+72):2= 54 -> 45
(94+78):2= 86 -> 68
(15+67):2= 41 -> 14


Still working on the second one...
"It is one of those instances where the reasoner can produce an effect which seems remarkable to his neighbor, because the latter has missed the one little point which is the basis of the deduction."
Sherlock Holmes
ayw

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Re: Lsteral Thinking XIII

Postby ayw » March 22nd, 2009, 4:58 pm

@Sayumi, Well done!!
Move, and the way will open.
Sayumi
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Re: Lsteral Thinking XIII

Postby Sayumi » March 22nd, 2009, 5:56 pm

Got it!!!!  ;D
Yay, this was fun! You made my day ayw!
Here it is!
it always is the only odd/even one
4678   (74)   3419
3224   (39)   8962
1572   (21)   6421
9839   (80)   3031
Last edited by Sayumi on March 22nd, 2009, 6:02 pm, edited 1 time in total.
"It is one of those instances where the reasoner can produce an effect which seems remarkable to his neighbor, because the latter has missed the one little point which is the basis of the deduction."
Sherlock Holmes
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Re: Lateral Thinking XIII

Postby Holmes » March 22nd, 2009, 8:04 pm

I hate this, not even spoilers can be put!!!  >:( >:(

The first one:
You sum the two numbers, divide it by two and read it backwards, so the last one is ...
(15+67):2 = 41 -- 14.

The second one, it is either odd or even, so the last one is ...
9839 -- 80 -- 3031


Have to continue this thread or find a Lateral Thinking XIV ... mmm  ???
Last edited by Holmes on March 22nd, 2009, 8:10 pm, edited 1 time in total.
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ayw

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Re: Lsteral Thinking XIII

Postby ayw » March 22nd, 2009, 11:19 pm

Sayumi, Holmes, clean sweep!

Yeah, too bad we can't use spoilers for the moment... I guess they'll have it fixed soon. Most other things seem to work, though.
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Sayumi
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Re: Lsteral Thinking XIII

Postby Sayumi » March 24th, 2009, 10:02 am

Okay... my turn... :)
9798   (30)   6495
8531   (22)   9742
3758   (46)   3752
7328   (    )   1217

and

11235 (9)   121416
2468   (5)   36912
000     (4)   888
876     (  )  19232931

modified version:
1 1 2 3 5...  (9)  ...12 14 16...
...2 4 6 8...  (5)  ...3 6 9 12...
...0 0 0...      (4)  ...8 8 8...
...8 7 6...      (  )  ...19 23 29 31...
Last edited by Sayumi on March 24th, 2009, 1:14 pm, edited 1 time in total.
"It is one of those instances where the reasoner can produce an effect which seems remarkable to his neighbor, because the latter has missed the one little point which is the basis of the deduction."
Sherlock Holmes
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Re: Lsteral Thinking XIII

Postby Holmes » March 24th, 2009, 11:29 am

Number 2 cuaght my curiousity:

This is what I find interesting:

112358 -- Fibonacci sequence
121416 -- 12+2=14 + 2= 16 so 12,14,16
2468 -- same as 121416
36912 -- all multiples of 3= 3,6,9,12
000 and 888 -- 3 identical numbers
876 -- numbers descending= 8,7,6
19232931 -- a sequence of prime numbers= 19,23,29,31 in order

Maybe this means nothing, maybe this is a hint, maybe I have to think a little more and I´ll get it, or maybe this is just a coincidence of Destiny.

EDIT: I think this is the answer, 3minutes after I posted  :P

I think all this sequences tell you that it´s all related, so maybe the numbers in the middle are also related. The top number is 9, followed by 5 and 4, 5+4= 9. So maybe the last number is x+4=5, x=1, so the last number is 1.
Last edited by Holmes on March 24th, 2009, 11:40 am, edited 1 time in total.
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Sayumi
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Re: Lsteral Thinking XIII

Postby Sayumi » March 24th, 2009, 11:53 am

@Holmes:
First part:
Yep, sequences are very important!

Second part:
Not the one I meant - it's not distinct enough... but a good idea!
"It is one of those instances where the reasoner can produce an effect which seems remarkable to his neighbor, because the latter has missed the one little point which is the basis of the deduction."
Sherlock Holmes
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Re: Lsteral Thinking XIII

Postby Holmes » March 24th, 2009, 12:29 pm

I think this might do it, if it doesn´t, I would have found 2 different answers for this one Sayumi, haha  :o

Here´s my answer,

First I tried to think the relationship between the numbers in the middle with the one at their side. So, 11235 (9) 121416,
if you lin this two and you sum, you get 233766, this made me think:" One number, two 3´s, one number, two 6´s, so maybe one number and two 9´s. 9 is the middle number.
After this 2468 (5) 36912,
you also line up and you sum the digits: 2+3, 4+6, 6+9, 8+12 and you get 5,10,15,20, multiples of 5 in order. 5 is the midle number.
Finally 000 (4) 888,
4x222=888. 4 is the middle number.
This cost me a lot, a relationship between 876 and 19232931, WTF!!! i made the same as the others, line up and sum, but ... terible. After that I continued with the general idea, and suddenly I thought: "Maybe I have to sum all the digits: 8+7+6+1+9+2+3+2+9+3+1= 51
51=17x3 -- 17 is the privious prime number 17,19,23 so.
because of all this I say that 3 is the last number.


I hope this is ok, if it is, I have to congratulate you for thinking this one that would gave most people a headache for a month(I´m included and this reminds me Lateral Thinking V, the one of the people, the dogs and the boat) After you say yes or no, I´ll think number 1. Would like to see aym thinking this one. Thanks again!
Last edited by Holmes on March 24th, 2009, 12:34 pm, edited 1 time in total.
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Sayumi
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Re: Lsteral Thinking XIII

Postby Sayumi » March 24th, 2009, 1:24 pm

@Holmes
It's still not the one I meant though I totally love your answer ;D ! The first answer was closer but the prime number part was right. I put up a modified version maybe that'll help to show what i'm looking for.... Hope you'll have another go at it. I'll send ayw a note to have a look at it as well :)
I guess there is more than one answer for it though-I just thought of this while being at school, so it's probably not flawless. But the answer is easier than what you came up with...

awww... I really miss the spoiler tags!
"It is one of those instances where the reasoner can produce an effect which seems remarkable to his neighbor, because the latter has missed the one little point which is the basis of the deduction."
Sherlock Holmes
Holmes
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Re: Lsteral Thinking XIII

Postby Holmes » March 24th, 2009, 6:38 pm

Although it´s wrong I really like to think taht answer, I´ll think about the modified one tomorrow at school: I have the the most boring subjects.
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