<PRE><B>Question 640424</B>
 A 2-digit number between 20 and 30 has 5 factors less than the number itself.
 When added together, the factors equal the number. What is the number?
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This is a perfect number, when all the factors add up the number itself
1 + 2 + 4 + 7 + 14 = 28 is the number
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6 is also a perfect number: 1 + 2 + 3; (as is 496)
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2,305,843,008,139,952,128 is also said to be a perfect number
 but I have not personally checked it out
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An interesting website: http://www.ask.com/wiki/List_of_perfect_numbers
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