A chest is locked with a three-digit code. You are given five clues: '6 8 2' has one correct digit in the correct position. '6 1 4' has one correct digit in the wrong position. '2 0 6' has two correct digits, both in wrong positions. '7 3 8' has no correct digits. '7 8 0' has one correct digit in the wrong position. What is the three-digit code?
042
From '7 3 8', digits 7, 3, and 8 are incorrect. In '7 8 0', 0 must be correct but not in position 3. In '6 8 2', 8 is wrong, leaving 6 in pos 1 or 2 in pos 3. If 6 were correct, it would contradict '6 1 4' (where 6 is in pos 1 but stated as wrong position). Thus 6 is wrong and 2 is in pos 3. In '2 0 6', 2 and 0 are correct; since 0 cannot be in pos 3 or 2, 0 is in pos 1. Finally, '6 1 4' leaves 4 for position 2.
About this riddle
Logic riddles give you a few facts and ask what must be true. List what you know, cross out what cannot be, and see what is left.
Difficulty: Hard. More like this: Logic riddles with answers or try Einstein's Logic Grid for a different kind of puzzle.
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