2005 AIME I Problems/Problem 3
Problem
How many positive integers have exactly three proper divisors, each of which is less than 50?
Solution
This problem needs a solution. If you have a solution for it, please help us out by adding it.
The following solution contains errors; please correct it: Having three proper divisors means that there are 4 regular divisors. So the number can be written as where and are primes. The primes under fifty are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, and 47. There are 15 of them. So there are such numbers.