alleryProper divisors 1, 2, 4, 7 and 14 add to a perfect number. Which?
A8
B12
C28
D24
Answer & Solution
Correct answer: C. 28
1. Proper divisors of 28 are 1, 2, 4, 7 and 14.
2. Their sum 1 + 2 + 4 + 7 + 14 = 28.
3. 8 gives 7 and 12 gives 16, so neither is perfect.
_Source: Wikipedia, Perfect number, lead section_
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