Regrouping for Double-Digit Subtraction

1. Two-Digit Subtraction – Regrouping Regrouping for Double-Digit Subtraction

2. Two-Digit Subtraction – Regrouping Two approaches: “10 First” Approach Common Approach

3. Two-Digit Subtraction – Regrouping 1. “10 First” Approach 23-16 6

4. Two-Digit Subtraction – Regrouping Start with subtracting the units column 23-16 36

5. Two-Digit Subtraction – Regrouping 23-16 First, put 3 on Mathline

6. Two-Digit Subtraction – Regrouping 23-16 6 Can we subtract six?

7. Two-Digit Subtraction – Regrouping 23-16 6 No, 3 is less than 6 So we need to regroup

8. Two-Digit Subtraction – Regrouping 23-16 6 10 First Approach!

9. Two-Digit Subtraction – Regrouping 23-16 6 Start by clearing the MathLine

10. Two-Digit Subtraction – Regrouping 23-16 6 Count 10 from right and move over

11. Two-Digit Subtraction – Regrouping 23-16 1 1 6 This is regrouping One ten becomes ten ones

12. Two-Digit Subtraction – Regrouping 23-16 1 1 6 Now put the 3 ones back

13. Two-Digit Subtraction – Regrouping 23-16 1 1 6 36 Now put the 3 ones back

14. Two-Digit Subtraction – Regrouping 23-16 1 1 6 36 See 13

15. Two-Digit Subtraction – Regrouping 23-16 1 1 6 36 Now take 13 minus 6 6 3 2 1 5 4

16. Two-Digit Subtraction – Regrouping 23-16 1 1 6 36 See 7 7

17. Two-Digit Subtraction – Regrouping 1 1 23-16 Now we clear the MathLine to subtract the tens column 7

18. Two-Digit Subtraction – Regrouping 23-16 7 1 1 Count ten rings on MathLine 7

19. Two-Digit Subtraction – Regrouping 23-16 7 1 1 Count ten rings on MathLine Then subtract 10 7

20. Two-Digit Subtraction – Regrouping 23-16 7 1 1 See zero on MathLine 0 7

21. Two-Digit Subtraction – Regrouping 2. Common Approach 23-16 6

22. Two-Digit Subtraction – Regrouping Start with subtracting the units column 23-16 36

23. Two-Digit Subtraction – Regrouping 23-16 First, put 3 on Mathline

24. Two-Digit Subtraction – Regrouping 23-16 6 Can we subtract six?

25. Two-Digit Subtraction – Regrouping 23-16 6 No, 3 is less than 6 So we need to regroup

26. Two-Digit Subtraction – Regrouping 23-16 6 Common Approach!

27. Two-Digit Subtraction – Regrouping 23-16 Count 10 rings from the right side to regroup. 1

28. Two-Digit Subtraction – Regrouping 23-16 Count 10 rings from the right side to regroup. 1 2

29. Two-Digit Subtraction – Regrouping 23-16 Count 10 rings from the right side to regroup. 1 2 3

30. Two-Digit Subtraction – Regrouping 23-16 Count 10 rings from the right side to regroup. 1 2 3 4

31. Two-Digit Subtraction – Regrouping 23-16 Count 10 rings from the right side to regroup. 1 2 3 4 5

32. Two-Digit Subtraction – Regrouping 23-16 Count 10 rings from the right side to regroup. 1 2 3 4 5 6

33. Two-Digit Subtraction – Regrouping 23-16 Count 10 rings from the right side to regroup. 1 2 3 4 5 6 7

34. Two-Digit Subtraction – Regrouping 23-16 Count 10 rings from the right side to regroup. 1 2 3 4 5 6 7 8

35. Two-Digit Subtraction – Regrouping 23-16 Count 10 rings from the right side to regroup. 1 2 3 4 5 6 7 8 9

36. Two-Digit Subtraction – Regrouping 23-16 Count 10 rings from the right side to regroup. 1 2 3 4 5 6 7 8 9 10

37. Two-Digit Subtraction – Regrouping Explain this ten came from the tens column 1 1 23-16 23-16 6 Move rings to the left. This is regrouping!

38. Two-Digit Subtraction – Regrouping 1 1 1 23-16 Next, subtract 13 minus 6 6 3 2 1 5 4

39. Two-Digit Subtraction – Regrouping 1 1 1 23-16 See 7 in the ones column 7

40. Two-Digit Subtraction – Regrouping 1 1 23-16 Now we clear the MathLine to subtract the tens column 7

41. Two-Digit Subtraction – Regrouping 23-16 7 1 1 Count ten rings on MathLine 7

42. Two-Digit Subtraction – Regrouping 23-16 7 1 1 Count ten rings on MathLine Then subtract 10 7

43. Two-Digit Subtraction – Regrouping 23-16 7 1 1 See zero on MathLine 0 7