I am a four-digit number with no repeating digits. My first digit is twice my last digit. My second digit is the sum of my first and last digits. My third digit is my second digit minus 1. The sum of all my digits is 17. What number am I?
4652
Let the digits be ABCD. A = 2D. B = A + D = 3D. C = B - 1 = 3D - 1. If D = 2, then A = 4, B = 6, C = 5. The sum 4 + 6 + 5 + 2 = 17, and all digits are unique.
About this riddle
Math riddles hide a calculation inside a short story. Pull out the numbers, work out what is being asked, and watch for a trick such as a unit change.
Difficulty: Hard. More like this: Math riddles with answers or try Target 24 for a different kind of puzzle.
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