Question 1132526
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what is the sum of all positive two-digit integers with exactly five positive {{{highlight(cross(integral))}}} <U>integer</U> factors 
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If you mean  " . . . with exactly five positive <U>divisors</U>", 


then there are 2 and only two such numbers. &nbsp;They are


&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;{{{2^4}}} = 16 &nbsp;&nbsp;with the divisors  &nbsp;1, 2, 4, 8 &nbsp;and &nbsp;16,  &nbsp;&nbsp;&nbsp;&nbsp;and


&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;{{{3^4}}} = 81 &nbsp;&nbsp;with the divisors  &nbsp;1, 3, 9, 27 &nbsp;and &nbsp;81.


The sum is  &nbsp;&nbsp;16 + 81, &nbsp;which you can easily calculate on your own.