A positive integer n is a perfect number provided that the sum of all the positive factors of n, including 1 and n, is equal to 2n. What is the sum of the reciprocals of all the positive factors of the perfect number 28?	Choose the correct choice from the following.
A) 1/4 B) 56/27 C) 2 D) 3 E) 4
Soln:   28 = 1*28   2*14   4*7   sum of reciprocals = 1+1/28+1/2+1/14+1/4+1/7=56/28= 
<gadget id="calculator">56/28</gadget>
<output>2</output>
2   ANSWER:2
<result>C</result>
A positive integer n is a perfect number provided that the sum of all the positive factors of n, including 1 and n, is equal to 2n. What is the sum of the reciprocals of all the positive factors of the perfect number 28?