Subtraction practice

Solve each problem. Use the scratch space if you need it.

1. 9 - 9=____
2. 9 - 1=____
3. 8 - 2=____
4. 1 - 1=____
5. 8 - 6=____
6. 9 - 9=____
7. 9 - 1=____
8. 1 - 1=____