Printable math worksheet featuring twelve 3-digit addition problems set on grid paper to assist with column alignment.

Let's solve each of the addition problems in the worksheet step by step. We'll go through them one at a time, adding the numbers carefully and showing the process.

---

1. 996 + 978

```
996
+ 978
-----
```

Start from the right:

- Units: 6 + 8 = 14 → write down 4, carry over 1
- Tens: 9 + 7 = 16, plus carry-over 1 = 17 → write down 7, carry over 1
- Hundreds: 9 + 9 = 18, plus carry-over 1 = 19 → write down 19

So:
996 + 978 = 1974

---

2. 896 + 968

```
896
+ 968
-----
```

- Units: 6 + 8 = 14 → write 4, carry 1
- Tens: 9 + 6 = 15, plus 1 = 16 → write 6, carry 1
- Hundreds: 8 + 9 = 17, plus 1 = 18 → write 18

896 + 968 = 1864

---

3. 795 + 998

```
795
+ 998
-----
```

- Units: 5 + 8 = 13 → write 3, carry 1
- Tens: 9 + 9 = 18, plus 1 = 19 → write 9, carry 1
- Hundreds: 7 + 9 = 16, plus 1 = 17 → write 17

795 + 998 = 1793

---

4. 598 + 958

```
598
+ 958
-----
```

- Units: 8 + 8 = 16 → write 6, carry 1
- Tens: 9 + 5 = 14, plus 1 = 15 → write 5, carry 1
- Hundreds: 5 + 9 = 14, plus 1 = 15 → write 15

598 + 958 = 1556

---

5. 597 + 938

```
597
+ 938
-----
```

- Units: 7 + 8 = 15 → write 5, carry 1
- Tens: 9 + 3 = 12, plus 1 = 13 → write 3, carry 1
- Hundreds: 5 + 9 = 14, plus 1 = 15 → write 15

597 + 938 = 1535

---

6. 596 + 928

```
596
+ 928
-----
```

- Units: 6 + 8 = 14 → write 4, carry 1
- Tens: 9 + 2 = 11, plus 1 = 12 → write 2, carry 1
- Hundreds: 5 + 9 = 14, plus 1 = 15 → write 15

596 + 928 = 1524

---

7. 595 + 968

```
595
+ 968
-----
```

- Units: 5 + 8 = 13 → write 3, carry 1
- Tens: 9 + 6 = 15, plus 1 = 16 → write 6, carry 1
- Hundreds: 5 + 9 = 14, plus 1 = 15 → write 15

595 + 968 = 1563

---

8. 594 + 978

```
594
+ 978
-----
```

- Units: 4 + 8 = 12 → write 2, carry 1
- Tens: 9 + 7 = 16, plus 1 = 17 → write 7, carry 1
- Hundreds: 5 + 9 = 14, plus 1 = 15 → write 15

594 + 978 = 1572

---

9. 593 + 998

```
593
+ 998
-----
```

- Units: 3 + 8 = 11 → write 1, carry 1
- Tens: 9 + 9 = 18, plus 1 = 19 → write 9, carry 1
- Hundreds: 5 + 9 = 14, plus 1 = 15 → write 15

593 + 998 = 1591

---

10. 599 + 978

```
599
+ 978
-----
```

- Units: 9 + 8 = 17 → write 7, carry 1
- Tens: 9 + 7 = 16, plus 1 = 17 → write 7, carry 1
- Hundreds: 5 + 9 = 14, plus 1 = 15 → write 15

599 + 978 = 1577

---

11. 678 + 543

```
678
+ 543
-----
```

- Units: 8 + 3 = 11 → write 1, carry 1
- Tens: 7 + 4 = 11, plus 1 = 12 → write 2, carry 1
- Hundreds: 6 + 5 = 11, plus 1 = 12 → write 12

678 + 543 = 1221

---

12. 876 + 555

```
876
+ 555
-----
```

- Units: 6 + 5 = 11 → write 1, carry 1
- Tens: 7 + 5 = 12, plus 1 = 13 → write 3, carry 1
- Hundreds: 8 + 5 = 13, plus 1 = 14 → write 14

876 + 555 = 1431

---

✔ Final Answers:

| Problem | Answer |
|----------------|--------|
| 996 + 978 | 1974 |
| 896 + 968 | 1864 |
| 795 + 998 | 1793 |
| 598 + 958 | 1556 |
| 597 + 938 | 1535 |
| 596 + 928 | 1524 |
| 595 + 968 | 1563 |
| 594 + 978 | 1572 |
| 593 + 998 | 1591 |
| 599 + 978 | 1577 |
| 678 + 543 | 1221 |
| 876 + 555 | 1431 |

---

🔍 Explanation:

Each problem involves adding three-digit numbers, which often results in carrying over digits to the next column (tens or hundreds). The key steps are:
1. Add from right to left (units → tens → hundreds).
2. If the sum in any column is 10 or more, carry over the extra digit to the next higher place.
3. Write down only the last digit of the sum in that column.

This kind of practice helps build mental math skills and accuracy in multi-digit addition.

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