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Let x be a two-digit number. If x > 0, and the sum of the digits of x is 9, then the sum of the digits of the number (x + 10) is:

*This question is included in Nova Press: Set E - Number Theory, question #21

The solution is

Posted: 01/03/2014 13:52

could it be a negative number?like -72?

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Contributor

Posted: 01/13/2014 17:33

Mak, that's a good point. The problem should have stated x>0.

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