Solve the following addition problems: 0 + 12, 0 + 18, 4 + 4, 4 + 6, 6 + 6

$$0 + 12 = 12$$

The answer is $\boxed{12}$.

$$0 + 18 = 18$$

The answer is $\boxed{18}$.

$$4 + 4 = 8$$

The answer is $\boxed{8}$.

$$4 + 6 = 10$$

The answer is $\boxed{10}$.

$$6 + 6 = 12$$

The answer is $\boxed{12}$.