Start with statement 2, eliminate 7, 3 and 8 as correct digits.
This leaves statement 5 with only the 0 (but in the wrong place)
Statement 3 tells us that 206 has 2 digits, but they're both in the wrong place.
So now... we know that 0 is correct, but it can't be in the middle spot (since 206 is wrong)
nor can it be in the last spot (since 780 is wrong). The first number MUST be 0
Statement 1 now tells us that (682 has 1 digit right and in the right place.
It can't be the 6 (since the first number is 0), it can't be the 8 (since 738 are all wrong)
So the last number MUST be 2.
Statement 4 tells us that one digit is right but in the wrong place. We know 6 is wrong;
since statement 1 has only has 1 right number and it's the 2. So this leaves the 1 and the 4.
But it CAN'T be the 1 because then the 1 would be right AND in the right place. So we know
the only correct number is in the wrong spot. 4 is correct but belongs in the middle position
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