This sheet offers 24 distinct problems for practicing the addition of three-digit numbers in columns.

3-digit addition worksheet with 24 math problems for students to solve.

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Show Answer Key & Explanations Step-by-step solution for: 3 Digit Addition Worksheets

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Let's solve each of the 3-digit addition problems step by step. I'll go through them one by one and explain the process, including how to handle carrying over when necessary.

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1) 607 + 328

```
607
+ 328
-----
```

- Ones place: 7 + 8 = 15 → write down 5, carry over 1
- Tens place: 0 + 2 = 2, plus carry-over 1 = 3
- Hundreds place: 6 + 3 = 9

✔ Answer: 935

---

2) 286 + 505

```
286
+ 505
-----
```

- Ones: 6 + 5 = 11 → write 1, carry 1
- Tens: 8 + 0 = 8, plus carry 1 = 9
- Hundreds: 2 + 5 = 7

✔ Answer: 791

---

3) 705 + 523

```
705
+ 523
-----
```

- Ones: 5 + 3 = 8
- Tens: 0 + 2 = 2
- Hundreds: 7 + 5 = 12

✔ Answer: 1228

---

4) 817 + 320

```
817
+ 320
-----
```

- Ones: 7 + 0 = 7
- Tens: 1 + 2 = 3
- Hundreds: 8 + 3 = 11

✔ Answer: 1137

---

5) 582 + 173

```
582
+ 173
-----
```

- Ones: 2 + 3 = 5
- Tens: 8 + 7 = 15 → write 5, carry 1
- Hundreds: 5 + 1 = 6, plus carry 1 = 7

✔ Answer: 755

---

6) 438 + 821

```
438
+ 821
-----
```

- Ones: 8 + 1 = 9
- Tens: 3 + 2 = 5
- Hundreds: 4 + 8 = 12

✔ Answer: 1259

---

7) 653 + 273

```
653
+ 273
-----
```

- Ones: 3 + 3 = 6
- Tens: 5 + 7 = 12 → write 2, carry 1
- Hundreds: 6 + 2 = 8, plus carry 1 = 9

✔ Answer: 926

---

8) 914 + 59

```
914
+ 59
-----
```

Align right:

```
914
+ 59
-----
```

- Ones: 4 + 9 = 13 → write 3, carry 1
- Tens: 1 + 5 = 6, plus carry 1 = 7
- Hundreds: 9 + 0 = 9

✔ Answer: 973

---

9) 348 + 296

```
348
+ 296
-----
```

- Ones: 8 + 6 = 14 → write 4, carry 1
- Tens: 4 + 9 = 13, plus carry 1 = 14 → write 4, carry 1
- Hundreds: 3 + 2 = 5, plus carry 1 = 6

✔ Answer: 644

---

10) 843 + 514

```
843
+ 514
-----
```

- Ones: 3 + 4 = 7
- Tens: 4 + 1 = 5
- Hundreds: 8 + 5 = 13

✔ Answer: 1357

---

11) 485 + 176

```
485
+ 176
-----
```

- Ones: 5 + 6 = 11 → write 1, carry 1
- Tens: 8 + 7 = 15, plus carry 1 = 16 → write 6, carry 1
- Hundreds: 4 + 1 = 5, plus carry 1 = 6

✔ Answer: 661

---

12) 624 + 365

```
624
+ 365
-----
```

- Ones: 4 + 5 = 9
- Tens: 2 + 6 = 8
- Hundreds: 6 + 3 = 9

✔ Answer: 989

---

13) 597 + 64

```
597
+ 64
-----
```

- Ones: 7 + 4 = 11 → write 1, carry 1
- Tens: 9 + 6 = 15, plus carry 1 = 16 → write 6, carry 1
- Hundreds: 5 + 0 = 5, plus carry 1 = 6

✔ Answer: 661

---

14) 357 + 482

```
357
+ 482
-----
```

- Ones: 7 + 2 = 9
- Tens: 5 + 8 = 13 → write 3, carry 1
- Hundreds: 3 + 4 = 7, plus carry 1 = 8

✔ Answer: 839

---

15) 615 + 426

```
615
+ 426
-----
```

- Ones: 5 + 6 = 11 → write 1, carry 1
- Tens: 1 + 2 = 3, plus carry 1 = 4
- Hundreds: 6 + 4 = 10

✔ Answer: 1041

---

16) 548 + 703

```
548
+ 703
-----
```

- Ones: 8 + 3 = 11 → write 1, carry 1
- Tens: 4 + 0 = 4, plus carry 1 = 5
- Hundreds: 5 + 7 = 12

✔ Answer: 1251

---

17) 917 + 351

```
917
+ 351
-----
```

- Ones: 7 + 1 = 8
- Tens: 1 + 5 = 6
- Hundreds: 9 + 3 = 12

✔ Answer: 1268

---

18) 652 + 275

```
652
+ 275
-----
```

- Ones: 2 + 5 = 7
- Tens: 5 + 7 = 12 → write 2, carry 1
- Hundreds: 6 + 2 = 8, plus carry 1 = 9

✔ Answer: 927

---

19) 846 + 372

```
846
+ 372
-----
```

- Ones: 6 + 2 = 8
- Tens: 4 + 7 = 11 → write 1, carry 1
- Hundreds: 8 + 3 = 11, plus carry 1 = 12

✔ Answer: 1218

---

20) 753 + 629

```
753
+ 629
-----
```

- Ones: 3 + 9 = 12 → write 2, carry 1
- Tens: 5 + 2 = 7, plus carry 1 = 8
- Hundreds: 7 + 6 = 13

✔ Answer: 1382

---

21) 418 + 607

```
418
+ 607
-----
```

- Ones: 8 + 7 = 15 → write 5, carry 1
- Tens: 1 + 0 = 1, plus carry 1 = 2
- Hundreds: 4 + 6 = 10

✔ Answer: 1025

---

22) 784 + 275

```
784
+ 275
-----
```

- Ones: 4 + 5 = 9
- Tens: 8 + 7 = 15 → write 5, carry 1
- Hundreds: 7 + 2 = 9, plus carry 1 = 10

✔ Answer: 1059

---

23) 984 + 66

```
984
+ 66
-----
```

- Ones: 4 + 6 = 10 → write 0, carry 1
- Tens: 8 + 6 = 14, plus carry 1 = 15 → write 5, carry 1
- Hundreds: 9 + 0 = 9, plus carry 1 = 10

✔ Answer: 1050

---

24) 687 + 536

```
687
+ 536
-----
```

- Ones: 7 + 6 = 13 → write 3, carry 1
- Tens: 8 + 3 = 11, plus carry 1 = 12 → write 2, carry 1
- Hundreds: 6 + 5 = 11, plus carry 1 = 12

✔ Answer: 1223

---

✔ Final Answers:

| Problem | Answer |
|--------|--------|
| 1) | 935 |
| 2) | 791 |
| 3) | 1228 |
| 4) | 1137 |
| 5) | 755 |
| 6) | 1259 |
| 7) | 926 |
| 8) | 973 |
| 9) | 644 |
| 10) | 1357 |
| 11) | 661 |
| 12) | 989 |
| 13) | 661 |
| 14) | 839 |
| 15) | 1041 |
| 16) | 1251 |
| 17) | 1268 |
| 18) | 927 |
| 19) | 1218 |
| 20) | 1382 |
| 21) | 1025 |
| 22) | 1059 |
| 23) | 1050 |
| 24) | 1223 |

---

🔍 Summary:

All problems involve adding two 3-digit numbers (or a 3-digit and a 2-digit number). The key steps are:
- Add digits from right to left (ones, tens, hundreds)
- Carry over when the sum in a column is 10 or more
- Be careful with multiple carries (e.g., tens place may cause a carry into hundreds)

Let me know if you'd like this as a printable answer sheet!

Parent Tip: Review the logic above to help your child master the concept of addition worksheet hundreds.

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