N is the set of real numbers that are factors of 12

{1, 2, 3, 4, 6}
{1, 2, 3, 4, 6, 12}
{1, 2, 3, 4, 5, 6, 8, 12}
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12}