Skill: Find common factors

A common factor is a whole number that divides two numbers evenly, with no remainder.

To find the common factors of $12$ and $18$:

1. List the factor pairs for $12$:

   • $1 \times 12$
   • $2 \times 6$
   • $3 \times 4$

   So, the factors of $12$ are
   $1, 2, 3, 4, 6, 12$.

2. List the factor pairs for $18$:

   • $1 \times 18$
   • $2 \times 9$
   • $3 \times 6$

   So, the factors of $18$ are
   $1, 2, 3, 6, 9, 18$.

3. Find the numbers that appear in both lists:

$$1,\ 2,\ 3,\ 6$$

Therefore, the common factors of $12$ and $18$ are $\boxed{1, 2, 3,\text{ and }6}$.

Remember: $1$ is a factor of every whole number. A factor divides a number evenly; a multiple is the result of multiplying a number by a whole number.