What is the greatest common factor of 28 and 42?

The greatest common factor (GCF) of two numbers is the largest number that divides both of them evenly. To find the GCF of 28 and 42, we can list the factors of each number:

Factors of 28: 1, 2, 4, 7, 14, 28 Factors of 42: 1, 2, 3, 6, 7, 14, 21, 42

The common factors of 28 and 42 are 1, 2, 7, and 14. The greatest common factor is 14. Therefore, the GCF of 28 and 42 is 14.