Decimal Addition and Subtraction worksheet for practicing math problems with tenths and hundredths.

Let's solve each of the decimal addition and subtraction problems step by step. We'll rewrite each problem vertically, aligning the decimal points, and then perform the operations.

---

a. 7.9 + 3.47

```
7.90
+ 3.47
------
11.37
```

Explanation:
We rewrite 7.9 as 7.90 to match the number of decimal places. Then add:

- 0 + 7 = 7 (hundredths)
- 9 + 4 = 13 → write 3, carry 1 (tenths)
- 7 + 3 + 1 (carry) = 11 → write 11

So, 7.9 + 3.47 = 11.37

---

b. 2.98 + 5.3

```
2.98
+ 5.30
------
8.28
```

Explanation:
Rewrite 5.3 as 5.30.

- 8 + 0 = 8 (hundredths)
- 9 + 3 = 12 → write 2, carry 1 (tenths)
- 2 + 5 + 1 = 8 (ones)

So, 2.98 + 5.3 = 8.28

---

c. 2 - 0.43

```
2.00
- 0.43
------
1.57
```

Explanation:
Rewrite 2 as 2.00.

- 0 - 3 → can't do, borrow: 10 - 3 = 7 (hundredths)
- 9 (after borrowing) - 4 = 5 (tenths)
- 1 (after borrowing) - 0 = 1 (ones)

So, 2 - 0.43 = 1.57

---

d. 21 + 4.09

```
21.00
+ 4.09
-------
25.09
```

Explanation:
Rewrite 21 as 21.00.

- 0 + 9 = 9 (hundredths)
- 0 + 0 = 0 (tenths)
- 1 + 4 = 5 (ones)
- 2 + 0 = 2 (tens)

So, 21 + 4.09 = 25.09

---

e. 55.78 - 4.4

```
55.78
- 4.40
-------
51.38
```

Explanation:
Rewrite 4.4 as 4.40.

- 8 - 0 = 8 (hundredths)
- 7 - 4 = 3 (tenths)
- 5 - 4 = 1 (ones)
- 5 - 0 = 5 (tens)

So, 55.78 - 4.4 = 51.38

---

f. 80.93 - 48

```
80.93
- 48.00
-------
32.93
```

Explanation:
Rewrite 48 as 48.00.

- 3 - 0 = 3 (hundredths)
- 9 - 0 = 9 (tenths)
- 0 - 8 → can't do, borrow: 10 - 8 = 2 (ones), but need to borrow from tens
- 7 (after borrowing) - 4 = 3 (tens)
- 8 becomes 7 after borrowing, then 7 - 4 = 3? Wait — let's go carefully:

Actually:
- 80.93
- 48.00

Start from right:
- 3 - 0 = 3
- 9 - 0 = 9
- 0 - 8 → borrow from 8 (tens): 10 - 8 = 2, but the 0 becomes 10, then borrow again?
Wait better:

Break it down:

```
80.93
-48.00
-------
```

- Hundredths: 3 - 0 = 3
- Tenths: 9 - 0 = 9
- Ones: 0 - 8 → can’t, borrow from tens
- Tens: 8 becomes 7, ones become 10
- Now ones: 10 - 8 = 2
- Tens: 7 - 4 = 3

So result: 32.93

Yes, 80.93 - 48 = 32.93

---

g. 7.05 + 4.6

```
7.05
+ 4.60
------
11.65
```

Explanation:
Rewrite 4.6 as 4.60.

- 5 + 0 = 5 (hundredths)
- 0 + 6 = 6 (tenths)
- 7 + 4 = 11 (ones)

So, 7.05 + 4.6 = 11.65

---

h. 94 - 4.8

```
94.00
- 4.80
-------
89.20
```

Explanation:
Rewrite 94 as 94.00, 4.8 as 4.80.

- 0 - 0 = 0 (hundredths)
- 0 - 8 → can't, borrow: 10 - 8 = 2 (tenths), but need to borrow
- Borrow 1 from 4 (ones), so 4 becomes 3, and tenths become 10
- But we need to subtract 8 from tenths: 10 - 8 = 2
- Now ones: 3 - 4 → can't, borrow from tens
- Tens: 9 becomes 8, ones become 13
- 13 - 4 = 9
- Tens: 8 - 0 = 8

So, 94 - 4.8 = 89.2

But wait: 94.00 - 4.80 = ?

Let’s compute:
- 94.00
- -4.80
- = 89.20 → yes

So, 89.20, or simply 89.2

Answer: 89.2

---

i. 32.15 + 24.15

```
32.15
+ 24.15
-------
56.30
```

Explanation:
Add directly:

- 5 + 5 = 10 → write 0, carry 1 (hundredths)
- 1 + 1 + 1 = 3 (tenths)
- 2 + 4 = 6 (ones)
- 3 + 2 = 5 (tens)

So, 32.15 + 24.15 = 56.30, or 56.3

---

j. 17.48 + 9.9

```
17.48
+ 9.90
-------
27.38
```

Explanation:
Rewrite 9.9 as 9.90.

- 8 + 0 = 8 (hundredths)
- 4 + 9 = 13 → write 3, carry 1 (tenths)
- 7 + 9 + 1 = 17 → write 7, carry 1 (ones)
- 1 + 0 + 1 = 2 (tens)

So, 17.48 + 9.9 = 27.38

---

k. 123.6 - 0.08

```
123.60
- 0.08
--------
123.52
```

Explanation:
Rewrite 123.6 as 123.60.

- 0 - 8 → can’t, borrow: 10 - 8 = 2 (hundredths)
- 5 (after borrowing) - 0 = 5 (tenths)
- Rest remains same

So, 123.6 - 0.08 = 123.52

---

l. 121.99 + 199.7

```
121.99
+ 199.70
---------
321.69
```

Explanation:
Rewrite 199.7 as 199.70.

- 9 + 0 = 9 (hundredths)
- 9 + 7 = 16 → write 6, carry 1 (tenths)
- 1 + 9 + 1 = 11 → write 1, carry 1 (ones)
- 1 + 9 + 1 = 11 → write 1, carry 1 (tens)
- 2 + 9 + 1 = 12 → write 2, carry 1 (hundreds)
- 1 + 1 = 2 (hundreds)

Wait, let's align:

```
121.99
+ 199.70
---------
```

- Hundredths: 9 + 0 = 9
- Tenths: 9 + 7 = 16 → write 6, carry 1
- Ones: 1 + 9 + 1 = 11 → write 1, carry 1
- Tens: 2 + 9 + 1 = 12 → write 2, carry 1
- Hundreds: 1 + 1 + 1 = 3

So: 321.69

Yes, 121.99 + 199.7 = 321.69

---

✔ Final Answers:

| Problem | Answer |
|--------|--------|
| a. 7.9 + 3.47 | 11.37 |
| b. 2.98 + 5.3 | 8.28 |
| c. 2 - 0.43 | 1.57 |
| d. 21 + 4.09 | 25.09 |
| e. 55.78 - 4.4 | 51.38 |
| f. 80.93 - 48 | 32.93 |
| g. 7.05 + 4.6 | 11.65 |
| h. 94 - 4.8 | 89.2 |
| i. 32.15 + 24.15 | 56.3 |
| j. 17.48 + 9.9 | 27.38 |
| k. 123.6 - 0.08 | 123.52 |
| l. 121.99 + 199.7 | 321.69 |

> Note: Always align decimals vertically and use zeros to fill missing decimal places before performing operations.

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