I think that was actually a joke. He surreptitiously only mentioned the prime factors of ten (2 and 5) and then listed all the factors of twelve (1, 2, 3, 4, 6,

I think that was actually a joke. He surreptitiously only mentioned the prime factors of ten (2 and 5) and then listed all the factors of twelve (1, 2, 3, 4, 6, 12). Ten, of course, has four factors: 1, 2, 5, 10 and twelve only has two prime factors as well: 2 and 3.