1. Whick of the followingis a pefect number , if a perfect is a number equals the sum of tall its positive divisors less than the number itself?
A) 16
B) 18
C) 20
D) 24
E) 28
這題答案是E, 我不懂 什麼 是perfect number???? Help~
2. A positive integer is a prime-saturated number if it is not equal to 1 and has no prime facotr large than or equal to the suqare root of the number itself. Which of the following is a prime-saturated number?
A) 15
b) 21
C) 44
D) 68
E) 70
這題答案是E, 我不懂 什麼 是perfect saturated number???? Help~