Explanation:
Perfect number is the positive integer which is equal to sum of proper divisors of the number.
Aliquot part is also called as proper divisor which means any divisor of the number which isn't equal to number itself.
Number : 6
Perfect divisors / Aliquot part = 1, 2, 3
Sum of the divisors = 1 + 2 + 3 = 6
Thus, 6 is a perfect number.
Number : 28
Perfect divisors / Aliquot part = 1, 2, 4, 7, 14
Sum of the divisors = 1 + 2 + 4 + 7 + 14 = 28
Thus, 28 is a perfect number.