Skill: Find the greatest common factor

A factor of a number divides it evenly, with no remainder. The greatest common factor (GCF) is the largest factor that two or more numbers share.

Example: Find the GCF of $24$ and $36$.

Step 1: List the factors of each number.

Factors of $24$:

$$1, 2, 3, 4, 6, 8, 12, 24$$

Factors of $36$:

$$1, 2, 3, 4, 6, 9, 12, 18, 36$$

Step 2: Identify the common factors.

The numbers that appear in both lists are:

$$1, 2, 3, 4, 6, 12$$

Step 3: Choose the greatest common factor.

The greatest number in the common-factor list is $12$.

Therefore,

$$\boxed{\text{GCF}(24,36)=12}$$

You can check that $12$ divides both numbers evenly:

$$24 \div 12=2 \qquad 36 \div 12=3$$