1. Adding an infinite value to a number returns:

2. Adding an infinite value to an infinite value returns:

3. Subtracting an infinite value from an infinite value returns:

4. Adding NaN to a number returns:

5. Adding NaN to NaN returns:

6. Adding NaN to an infinite value returns:

7. Adding NULL to a number returns:

8. Adding NULL to NULL returns:

9. Adding NULL to an infinite value returns:

10. Adding NULL to NaN returns:

11. Adding NA to a number returns:

12. Adding NA to NA returns:

13. Adding NA to an infinite value returns:

14. Adding NA to NaN returns:

15. Adding NA to NULL returns:

Notes: