2. MENTAL MATH

3. Rounding Addition and Subtraction Strategy: Estimate the answer by rounding each number to the nearest hundred Examples: 32 30 45 50 + 47 +50 -23 - 20 80 30

4. Practice with… Estimation by Rounding

5. 52 +28 50 +30 80

6. 89 - 68 90 - 70 20

7. 72 +16 70 +20 90

8. 37 - 28 40 - 30 10

9. 55 - 42 60 - 40 20

10. Timed Quiz Beginning with the next slide you will have 10 seconds to answer each question using the mental math strategy just practiced. There will be 10 questions to do. Put the title “Mental Math” at the top of your page, your name to the right, and then numbers 1 to 10 below. Only your answer will go beside the question number. Your page should look like the following:

11. Mental Math Susan Black 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. NOW…. Get ready to begin….

12. Question 1 48 - 27

13. Question 2 74 + 36

14. Question 3 69 - 54

15. Question 4 83 + 56

16. Question 5 27 - 19

17. Question 6 85 + 34

18. Question 7 43 - 16

19. Question 8 71 + 35

20. Question 9 98 - 33

21. Question 10 51 + 29

22. Now get ready to check your answers… 1.20 2.110 3.20 4.140 5.10 6.120 7.20 8.110 9.70 10.80