Fill in the blanks with the correct number.

1. 4 + 8 = 9 + ___

2. 8 + 4 = 2 + ___

3. 7 + 3 = 1 + ___

4. 10 + 10 = 20 + ___

5. 4 + ___ = 10 + 6

6. 2 + ___ = 3 + 5

7. 8 + 3 = 10 + ___

8. 5 + 6 = 1 + ___

9. 4 + 10 = 9 + ___

10. 9 + 9 = 8 + ___

11. 1 + ___ = 7 + 7

12. 18 + ___ = 10 + 10

13. ___ + 5 = 10 + 0

14. 2 + 9 = ___ + 7

15. 17 + 3 = 16 + ___

16. 16 + 4 = 17 + ___