what is the greatest common factor of the numbers 12 and 16
If you break a number down to it's prime factorization you can always determine the GCF.
What that means is you write the number as the product of only prime numbers.
12 = 2 * 2 * 3
16 = 2 * 2 * 2 * 2
Remember the C in GCF means Common
What do 12 and 16 have in common?
2 * 2 or 4