This worksheet provides a balanced mix of addition and subtraction problems to help students master 3-digit arithmetic.

Let’s solve each problem one by one. We’ll do the addition problems first, then the subtraction problems. I’ll show my work so you can follow along.

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Addition Problems:

1. 147 + 65
Start from the right:
7 + 5 = 12 → write down 2, carry over 1
4 + 6 = 10, plus the carried 1 = 11 → write down 1, carry over 1
1 + 0 (no digit) + carried 1 = 2
→ 212

2. 249 + 54
9 + 4 = 13 → write 3, carry 1
4 + 5 = 9, plus 1 = 10 → write 0, carry 1
2 + 0 + 1 = 3
→ 303

3. 480 + 96
0 + 6 = 6
8 + 9 = 17 → write 7, carry 1
4 + 0 + 1 = 5
→ 576

4. 724 + 77
4 + 7 = 11 → write 1, carry 1
2 + 7 = 9, plus 1 = 10 → write 0, carry 1
7 + 0 + 1 = 8
→ 801

5. 338 + 164
8 + 4 = 12 → write 2, carry 1
3 + 6 = 9, plus 1 = 10 → write 0, carry 1
3 + 1 = 4, plus 1 = 5
→ 502

6. 761 + 139
1 + 9 = 10 → write 0, carry 1
6 + 3 = 9, plus 1 = 10 → write 0, carry 1
7 + 1 = 8, plus 1 = 9
→ 900

7. 623 + 479
3 + 9 = 12 → write 2, carry 1
2 + 7 = 9, plus 1 = 10 → write 0, carry 1
6 + 4 = 10, plus 1 = 11 → write 11
→ 1102

8. 584 + 215
4 + 5 = 9
8 + 1 = 9
5 + 2 = 7
→ 799

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Subtraction Problems:

9. 328 - 68
8 - 8 = 0
2 - 6 → can’t do, borrow from 3 → 12 - 6 = 6, and 3 becomes 2
2 - 0 = 2
→ 260

10. 169 - 74
9 - 4 = 5
6 - 7 → can’t do, borrow from 1 → 16 - 7 = 9, and 1 becomes 0
0 - 0 = 0 (we don’t write leading zero)
→ 95

11. 943 - 52
3 - 2 = 1
4 - 5 → can’t do, borrow from 9 → 14 - 5 = 9, and 9 becomes 8
8 - 0 = 8
→ 891

12. 517 - 63
7 - 3 = 4
1 - 6 → can’t do, borrow from 5 → 11 - 6 = 5, and 5 becomes 4
4 - 0 = 4
→ 454

13. 836 - 268
6 - 8 → can’t do, borrow from 3 → 16 - 8 = 8, 3 becomes 2
2 - 6 → can’t do, borrow from 8 → 12 - 6 = 6, 8 becomes 7
7 - 2 = 5
→ 568

14. 545 - 385
5 - 5 = 0
4 - 8 → can’t do, borrow from 5 → 14 - 8 = 6, 5 becomes 4
4 - 3 = 1
→ 160

15. 905 - 628
5 - 8 → can’t do, borrow from 0 → but 0 has nothing to give! So we go to 9.
Borrow 1 from 9 → 9 becomes 8, 0 becomes 10. Now borrow 1 from that 10 → 10 becomes 9, and 5 becomes 15.
15 - 8 = 7
9 - 2 = 7
8 - 6 = 2
→ 277

16. 734 - 461
4 - 1 = 3
3 - 6 → can’t do, borrow from 7 → 13 - 6 = 7, 7 becomes 6
6 - 4 = 2
→ 273

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Final Answer:
212, 303, 576, 801, 502, 900, 1102, 799, 260, 95, 891, 454, 568, 160, 277, 273