A. Quick Addition
Do these problems in your head. Write only the answers.
- 4 + 9 =
- 40 + 90 =
- 20 + 90 =
- 20 + 30 =
- 30 + 50 =
- 40 + 60 =
- 10 + 90 =
- 60 + 80 =
- 80 + 70 =
- Show or tell your strategy for Problem I.