What's intriguing to me is not the solution but how I arrived at the solution. I'll try and reconstruct my thought processes, row by row.
Row 1: This doesn't tell us very much on its own.
Row 2: The 6 is in the same position as it was in the first row. If the first row has one correct number which is in the correct position, then this number can't be 6.
Row 3: As the 6 has been ruled out, we now know that two of the three numbers are 2 and 0 and that they are in the wrong position.
Row 4: This doesn't tell us very much on its own.
Row 5: The comment from row 4 tells us that 7 and 8 are wrong, so we know that 2 is one of the numbers – we knew this from row 3. But we now have the additional information that position 3 is the wrong place, and from row 3 we know that position 2 is also wrong – so the first digit in the solution must be 0.
Once we know the first digit and position, the rest can be calculated. The second number is 2 and should to be in position 3 (see row 1 – 6 and 8 have now been ruled out). So what is the number in position 2? Row 2 tells us that there is one correct number but in the wrong place. As 6 has been ruled out, this leaves us 1 and 4; the final number can't be 1 as 'correct number, wrong place' would put it in position 3 – which has already been filled by 2. Thus the middle digit to the solution must be 4, giving the solution 042.
Hmmm – 42 … the answer to life, the universe and everything.
Row 2: The 6 is in the same position as it was in the first row. If the first row has one correct number which is in the correct position, then this number can't be 6.
Row 3: As the 6 has been ruled out, we now know that two of the three numbers are 2 and 0 and that they are in the wrong position.
Row 4: This doesn't tell us very much on its own.
Row 5: The comment from row 4 tells us that 7 and 8 are wrong, so we know that 2 is one of the numbers – we knew this from row 3. But we now have the additional information that position 3 is the wrong place, and from row 3 we know that position 2 is also wrong – so the first digit in the solution must be 0.
Once we know the first digit and position, the rest can be calculated. The second number is 2 and should to be in position 3 (see row 1 – 6 and 8 have now been ruled out). So what is the number in position 2? Row 2 tells us that there is one correct number but in the wrong place. As 6 has been ruled out, this leaves us 1 and 4; the final number can't be 1 as 'correct number, wrong place' would put it in position 3 – which has already been filled by 2. Thus the middle digit to the solution must be 4, giving the solution 042.
Hmmm – 42 … the answer to life, the universe and everything.
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