A treasure chest is locked with a 3-digit combination. Clues: 682 gives one correct digit in the correct place. 614 gives one correct digit in the wrong place. 206 gives two correct digits in the wrong place. 738 gives no correct digits. 780 gives one correct digit in the wrong place. What is the correct combination?
042
From 738 (all wrong), 7, 3, and 8 are eliminated. Looking at 682: 8 is eliminated, leaving 6 or 2. From 206, two digits are correct in the wrong place; since 6 is present, either 2 and 0 or 2 and 6 are correct. But 6 can't be in the wrong place twice if it's right/wrong. Let's check 614: 6 or 1 or 4 is correct. If 2 is in 682 (right place), and 206 has 2, 0, 6 (two correct, wrong place), then 2 must be in position 3 (from 682). Then in 206, 2 is in position 1 (wrong place, matches pos 3), 0 and 6 are correct. If 0 is correct, in 780, 0 is present (and 7, 8 are out). In 780, 0 gives one correct digit in the wrong place (position 3 in 780, so position 1 or 2 in final). Since position 3 is taken by 2, 0 must be in position 2. Now we have _ 0 2. Looking at 614: 614 has 6, 1, 4. 6 was eliminated or used. 4 must be the correct digit in the wrong place (position 3 in 614, so position 1). Thus, the combination is 042? Wait, 4 is in position 3 in 614, so in the combination it must be in position 1 or 2. We have _ 0 2, so position 1 must be 4. Combination: 402.
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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