30
It is 2310.
625
The only number that ONLY has two and five as factors is 10, which has two digits, so there are no numbers that are three digits long and ONLY have two and five for factors. However, if you are asking what the largest three digit number that has two and five for factors, it would be the largest three digit number with ten as a factor, as ten the the LCM of two and five, and that would be 390.
Any three-digit multiple of 60, from 120 to 960, has the first five counting numbers as factors.
The next square number after ten (which is not a square number) is 16. Sixteen has five factors.
There are no prime numbers with three factors. By definition, a prime number has exactly two factors - 1 and itself.
3
15
Since five, two, and three are all prime, the lowest common denominator is 30 or 2 * 3 * 5.
210
720.
2