What is the gcf of 12 and 20?

The greatest common factor (GCF) of 12 and 20 is 4. This is because 4 is the largest number that can evenly divide both 12 and 20 without leaving a remainder. The factors of 12 are 1, 2, 3, 4, 6, and 12, while the factors of 20 are 1, 2, 4, 5, 10, and 20. The only common factor between 12 and 20 that is also the greatest is 4, making it the GCF of 12 and 20.