A digital vault code has four digits. The first digit is half the second. The second digit is twice the third. The third digit is three times the fourth. If the final digit is 1, what is the complete vault code?
6321.
Fourth digit = 1. Third digit = 3 x 1 = 3. Second digit = 2 x 3 = 6. First digit = half of 6 = 3? Wait. First digit is half the second (half of 6 is 3). So code is 3631. Let's check: First is 3, second is 6 (3 is half of 6). Second is 6, which is twice the third (3). Third is 3, which is three times the fourth (1). Code is 3631.
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: Medium. More like this: Logic riddles with answers or try Einstein's Logic Grid for a different kind of puzzle.
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