What is the common factor of 18 and 24?

To determine the common factor of 18 and 24, we first need to find the factors of each number. The factors of 18 are 1, 2, 3, 6, 9, and 18, while the factors of 24 are 1, 2, 3, 4, 6, 8, 12, and 24.

A common factor is a number that appears in both lists of factors. Looking at the two lists, we can identify the numbers that appear in both: 1, 2, 3, and 6. Among these, the largest common factor is 6, because it is the greatest number that divides both 18 and 24 without leaving a remainder.

As such, 6 is the correct answer, being the greatest common factor of the two numbers.