I am a two-digit number. My tens digit is twice my units digit, and the sum of my digits is six. What number am I?
42
Let tens be t and units be u. t = 2u and t + u = 6. Substituting 2u for t gives 3u = 6, so u = 2 and t = 4.
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: Easy. More like this: Math riddles with answers or try Target 24 for a different kind of puzzle.
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