Question

4. The number 4 is the smallest positive integer that has exactly three factors: 1, 2, and 4. If kis the next-

highest integer that also has exactly three factors, what is the sum of the three factors of K?
F. 13
G. 14
H. 16
J. 18
K. 20

Answer 1

Answer: F: 13

Explanation:

All positive integer having exactly 3 factors are square of a prime number:

2²,3²,5²,7²,11²,13²,17²,...

The next highest integer that also has exactly three factors is 3²=9

Sum of divisors=1+3+9=13

Answer 13