Solve the following addition problems: 0 + 4, 0 + 7, 5 + 0, 0 + 8, 4 + 0, 0 + 6.

For $0 + 4$:

$$0 + 4 = 4$$

The sum is $\boxed{\text{4}}$.
For $0 + 7$:

$$0 + 7 = 7$$

The sum is $\boxed{\text{7}}$.
For $5 + 0$:

$$5 + 0 = 5$$

The sum is $\boxed{\text{5}}$.

For $0 + 8$:

$$0 + 8 = 8$$

The sum is $\boxed{\text{8}}$.
For $4 + 0$:

$$4 + 0 = 4$$

The sum is $\boxed{\text{4}}$.
For $0 + 6$:

$$0 + 6 = 6$$

The sum is $\boxed{\text{6}}$.