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IF

7 - 3 = 10124
6 + 3 = 3279
5 – 2 = 763
11 + 2 = 92613

Then,

15 - 3 =? 

Any ideas ? I dont know how I am supposed to go about solving puzzles like this one ? is there any strategy ? any algorithm ?

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1  
That is one weird way to use +, -, or =... –  J. M. Nov 24 '11 at 5:40
    
@J.M. is it a symbolic question ? or is based on number representation ? any ideas ? –  Wildling Nov 24 '11 at 5:42
    
I'm just noting that those symbols you're using do not seem to be playing their conventional uses in your question. –  J. M. Nov 24 '11 at 5:46
3  
All of the "answers" end in what the actual answer should be (4,9,3,13), and start with the reverse operation (7-3 => 7+3 => 10 -- and similarly 6-3 = 3, 5+2 = 7, 11-2=9). –  Thomas Belulovich Nov 24 '11 at 5:48
    
12 =D lol... kidding. The problem with this puzzle is that whatever answer we get we won't be satisfied with it. –  Patrick Da Silva Nov 24 '11 at 5:49

4 Answers 4

up vote 8 down vote accepted

This is all I can come up with:

1: Do the operation, the answer to that will be placed on the far right:

$ \begin{align} 7-3 &= 4 \\ 6 + 3 &=9 \\ 5-2 &= 3 \\ 11 + 2 &= 13 \end{align}$

2: Take the solution from above, multiply by the second digit in the original expression. Place it to the left of the answer we got in 1.:

$ \begin{align} 4\cdot 3 &= 12 \\ 9\cdot 3&=27 \\ 3\cdot 2&= 6 \\ 13 \cdot 2 &= 26 \end{align}$

So, we have

$ \begin{align} 124 \\ 279 \\ 63 \\ 2613 \end{align}$

3: If the original operation was addition, subtract, and vice versa. Stick this number to the left of the concatenated solutions to 1 and 2:

$ \begin{align} 7+3 &= 10 \\ 6 - 3 &=3 \\ 5+2 &= 7 \\ 11 - 2 &= 9 \end{align}$

Thus, we have

$ \begin{align} 10124 \\ 3279 \\ 763 \\ 92613 \end{align}$

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You were 3 mins behind Thomas's answer, but i guess it took you more than 3 mins to format this answer. Hence selected your answer cos it was the fastest. –  Wildling Nov 24 '11 at 6:17

It would be $15-3 = 183612$. Answers are $(\text{opposite operation})(\text{answer} \times\text{second operand})(\text{actual computation})$

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WARNING: full answer

Note that 7 + 3 = 10, (7-3)*3 = 12, 7 - 3 = 4 Concatenate to get 10124

For the next one, 6 - 3 = 3, (6+3)*3 = 27, and 6+3 = 9 Concatenate to get 3279

Do a similar process for the other two. Its a weird pattern, but its there. And there isn't a general way to solve stuff like that, its just pattern recognition.

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ya, its pattern recognition; and you sir, rock at it ! –  Wildling Nov 24 '11 at 5:53

15-3 =?

(15+3)((15-3)*3)(15-3)

183612

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4  
Yes, that is what all the other answers have said. –  Zev Chonoles Nov 28 '11 at 9:52

protected by Zev Chonoles Nov 28 '11 at 9:52

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