1. 3rd – 5th grade Subtraction
Adding Up

2. Category 1 “Adding up strategy incorporating two ideas:
The whole is a multiple of ten or one hundred, and
The subtrahend is close to a multiple of ten or a landmark number.”
Parrish, S. (2010). Number talks: Helping children build mental math and computation strategies, grades K-5. Sausalito, CA: Math Solutions.

3. 20 – – – 9 20 – 8

4. 30 – – – – 12

5. 40 – – – – 19

6. 50 – – – – 24

7. 60 – – – – 29

8. 70 – – – – 34

9. 80 – – – – 39

10. 90 – – – – 44

11. 100 – – – – 44

12. Category 2
“The following number talks include computation problems where the whole is a multiple of ten or one hundred, and the subtrahend is close to a multiple of ten or a landmark number.” Parrish, S. (2010). Number talks: Helping children build mental math and computation strategies, grades K-5. Sausalito, CA: Math Solutions.

13. 100 – – – – 37

14. 150 – – – – 49

15. 200 – – – – 99

16. 250 – – – – 149

17. 300 – – – – 149

18. 400 – – – – 199

19. 500 – – – – 249

20. 750 – – – – 324

21. 1000 – – – – 499

22. Category 3
“The following number talks consists of computation problems where the whole is no longer an exact multiple of ten or one hundred, and the subtrahend is a farther distance from the whole.” Parrish, S. (2010). Number talks: Helping children build mental math and computation strategies, grades K-5. Sausalito, CA: Math Solutions.

23. 50 – – – – 37

24. 80 – – – – 36

25. 70 – – – – 39

26. 100 – – – – 83

27. 100 – – – – 89

28. 200 – – – – 198

29. 300 – – – – 287

30. 400 – – – – 298

31. 500 – – – – 671