What is the method to determine the greatest common factor (GCF)?

To find the greatest common factor (GCF) of two or more numbers, the method involves identifying the factors of each number and then determining which factors they have in common. By listing the factors of each number and circling the ones that appear in all lists, one can easily identify the common factors. The greatest of these common factors is the GCF.

For example, if you are finding the GCF of 12 and 18, the factors of 12 are 1, 2, 3, 4, 6, 12, and the factors of 18 are 1, 2, 3, 6, 9, 18. The common factors are 1, 2, 3, and 6, so the GCF is 6. This method ensures that all shared factors are acknowledged, and the largest one is selected, effectively fulfilling the requirement of finding the GCF.

Other methods, like listing multiples or using a formula, do not accurately determine the GCF and can be confusing. The method involving subtraction does not reliably yield information about shared factors either. Therefore, the correct approach involves identifying and circling common factors.