To solve this problem, we must do a method of trial and error to find
for the next highest integer with exactly three factors. We know that the value
of k must be greater than 4, therefore by using trial and error to find for the
correct answer:
Factors of 5:1, 5
Factors of 6:1, 2, 3, 6
Factors of 7:1, 7
Factors of 8:1, 2, 4, 8
Factors of 9:1, 3, 9
Therefore we stop at 9 since this is already our answer. It has exactly
three factors.