Let's solve each of the 2-digit mixed addition and subtraction problems
with regrouping step by step. I'll go through each problem, showing the work and explaining where regrouping is needed.
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1. 56 + 46
- Add ones: 6 + 6 = 12 → write down 2, carry over 1
- Add tens: 5 + 4 + 1 (carry) = 10
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Answer: 102
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2. 60 - 28
- Ones: 0 - 8 → can't do, so borrow from tens
- 60 becomes 5 tens and 10 ones
- 10 - 8 = 2
- Tens: 5 - 2 = 3
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Answer: 32
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3. 81 - 27
- Ones: 1 - 7 → can't do, borrow from tens
- 81 → 7 tens and 11 ones
- 11 - 7 = 4
- Tens: 7 - 2 = 5
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Answer: 54
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4. 59 + 16
- Ones: 9 + 6 = 15 → write 5, carry 1
- Tens: 5 + 1 + 1 = 7
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Answer: 75
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5. 77 + 24
- Ones: 7 + 4 = 11 → write 1, carry 1
- Tens: 7 + 2 + 1 = 10
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Answer: 101
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6. 45 + 16
- Ones: 5 + 6 = 11 → write 1, carry 1
- Tens: 4 + 1 + 1 = 6
-
Answer: 61
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7. 42 - 37
- Ones: 2 - 7 → can't do, borrow from tens
- 42 → 3 tens and 12 ones
- 12 - 7 = 5
- Tens: 3 - 3 = 0
-
Answer: 5
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8. 69 + 22
- Ones: 9 + 2 = 11 → write 1, carry 1
- Tens: 6 + 2 + 1 = 9
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Answer: 91
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9. 28 - 19
- Ones: 8 - 9 → can't do, borrow from tens
- 28 → 1 ten and 18 ones
- 18 - 9 = 9
- Tens: 1 - 1 = 0
-
Answer: 9
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10. 99 + 53
- Ones: 9 + 3 = 12 → write 2, carry 1
- Tens: 9 + 5 + 1 = 15
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Answer: 152
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11. 28 - 21
- Ones: 8 - 1 = 7
- Tens: 2 - 2 = 0
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Answer: 7
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12. 78 - 19
- Ones: 8 - 9 → can't do, borrow from tens
- 78 → 6 tens and 18 ones
- 18 - 9 = 9
- Tens: 6 - 1 = 5
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Answer: 59
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13. 38 + 38
- Ones: 8 + 8 = 16 → write 6, carry 1
- Tens: 3 + 3 + 1 = 7
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Answer: 76
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14. 82 - 68
- Ones: 2 - 8 → can't do, borrow from tens
- 82 → 7 tens and 12 ones
- 12 - 8 = 4
- Tens: 7 - 6 = 1
-
Answer: 14
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15. 95 - 77
- Ones: 5 - 7 → can't do, borrow from tens
- 95 → 8 tens and 15 ones
- 15 - 7 = 8
- Tens: 8 - 7 = 1
-
Answer: 18
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16. 98 - 78
- Ones: 8 - 8 = 0
- Tens: 9 - 7 = 2
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Answer: 20
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17. 68 - 29
- Ones: 8 - 9 → can't do, borrow from tens
- 68 → 5 tens and 18 ones
- 18 - 9 = 9
- Tens: 5 - 2 = 3
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Answer: 39
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18. 57 - 18
- Ones: 7 - 8 → can't do, borrow from tens
- 57 → 4 tens and 17 ones
- 17 - 8 = 9
- Tens: 4 - 1 = 3
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Answer: 39
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19. 99 + 99
- Ones: 9 + 9 = 18 → write 8, carry 1
- Tens: 9 + 9 + 1 = 19 → write 9, carry 1
- Hundreds: 1
-
Answer: 198
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20. 74 + 68
- Ones: 4 + 8 = 12 → write 2, carry 1
- Tens: 7 + 6 + 1 = 14
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Answer: 142
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✔ Final Answers:
| Problem | Answer |
|--------|--------|
| 1 | 102 |
| 2 | 32 |
| 3 | 54 |
| 4 | 75 |
| 5 | 101 |
| 6 | 61 |
| 7 | 5 |
| 8 | 91 |
| 9 | 9 |
| 10 | 152 |
| 11 | 7 |
| 12 | 59 |
| 13 | 76 |
| 14 | 14 |
| 15 | 18 |
| 16 | 20 |
| 17 | 39 |
| 18 | 39 |
| 19 | 198 |
| 20 | 142 |
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🔍 Summary:
-
Regrouping was used in:
- Addition: when sum of ones > 9 (e.g., 56+46)
- Subtraction: when top digit < bottom digit (e.g., 60-28)
- Always check
ones place first, then
tens, and handle borrowing or carrying accordingly.
Let me know if you'd like a printable version or visual steps!
Parent Tip: Review the logic above to help your child master the concept of addition and subtraction with regrouping worksheet 3rd grade.
