What is the highest common factor (HCF) of 18 and 24?

To find the highest common factor (HCF) of 18 and 24, we begin by determining the factors of each number.

The factors of 18 are:

• 1, 2, 3, 6, 9, 18

The factors of 24 are:

• 1, 2, 3, 4, 6, 8, 12, 24

Next, we identify the common factors between the two sets. Both 18 and 24 share the factors:

• 1, 2, 3, 6

Among these common factors, we need to find the highest one. The largest number in this list is 6.

Thus, the highest common factor of 18 and 24 is 6, which confirms the reasoning behind selecting this option as the correct answer.