I am a two-digit perfect number: the sum of all my proper divisors equals myself, and the sum of my two digits is 10. What number am I?
28
The proper divisors of 28 are 1, 2, 4, 7, and 14. Their sum is 1 + 2 + 4 + 7 + 14 = 28. The sum of the digits is 2 + 8 = 10.
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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