How many numbers are there less than thirty have exactly 6 factors?

Answer 1

Numbers with exactly 6 factors are perfect squares of prime numbers. The prime factorization of a number with exactly 6 factors is in the form ( p^2 ), where ( p ) is a Prime number. There are 10 prime numbers less than 30: 2, 3, 5, 7, 11, 13, 17, 19, 23, and 29. So, there are 10 numbers less than 30 that have exactly 6 factors.

Answer 2

Four numbers less than thirty, 12, 18, 20, and 28, each have exactly 6 factors.