what is the greatest common factor between 12 and 13?
['The prime factorization of 12 is: 2 x 2 x 3.', 'The prime factorization of 13 is: 13.', 'The prime factors and multiplicities 12 and 13 have in common are: 1.', '1 is the gcf of 12 and 13.', 'gcf(12,13) = 1.']