Math worksheet for practicing decimal addition and subtraction problems.

Here are the solutions to the math problems. I have calculated each one carefully.

Left Column:

1. 22.774 + 8.874
* Add the thousandths: $4 + 4 = 8$
* Add the hundredths: $7 + 7 = 14$ (write 4, carry 1)
* Add the tenths: $7 + 8 + 1 \text{ (carry)} = 16$ (write 6, carry 1)
* Add the ones: $2 + 8 + 1 \text{ (carry)} = 11$ (write 1, carry 1)
* Add the tens: $2 + 1 \text{ (carry)} = 3$
* Result: 31.648

2. 66.344 - 33.122
* Subtract thousandths: $4 - 2 = 2$
* Subtract hundredths: $4 - 2 = 2$
* Subtract tenths: $3 - 1 = 2$
* Subtract ones: $6 - 3 = 3$
* Subtract tens: $6 - 3 = 3$
* Result: 33.222

3. 9.8 - 0.8
* Subtract tenths: $8 - 8 = 0$
* Subtract ones: $9 - 0 = 9$
* Result: 9 (or 9.0)

4. 19.19 - 17.17
* Subtract hundredths: $9 - 7 = 2$
* Subtract tenths: $1 - 1 = 0$
* Subtract ones: $9 - 7 = 2$
* Subtract tens: $1 - 1 = 0$
* Result: 2.02

5. 9.3 - 4.9
* Borrow from the 9 to make it an 8. The 3 becomes 13.
* Subtract tenths: $13 - 9 = 4$
* Subtract ones: $8 - 4 = 4$
* Result: 4.4

6. 8.7 + 6.63
* Think of 8.7 as 8.70.
* Add hundredths: $0 + 3 = 3$
* Add tenths: $7 + 6 = 13$ (write 3, carry 1)
* Add ones: $8 + 6 + 1 \text{ (carry)} = 15$
* Result: 15.33

7. 0.17 - 0.09
* Borrow from the 1 to make it a 0. The 7 becomes 17.
* Subtract hundredths: $17 - 9 = 8$
* Subtract tenths: $0 - 0 = 0$
* Result: 0.08

8. 14.33 - 2.17
* Borrow from the 3 (tenths) to make the 3 (hundredths) a 13. The tenths become 2.
* Subtract hundredths: $13 - 7 = 6$
* Subtract tenths: $2 - 1 = 1$
* Subtract ones: $4 - 2 = 2$
* Subtract tens: $1 - 0 = 1$
* Result: 12.16

***

Right Column:

9. 99.37 + 88.42
* Add hundredths: $7 + 2 = 9$
* Add tenths: $3 + 4 = 7$
* Add ones: $9 + 8 = 17$ (write 7, carry 1)
* Add tens: $9 + 8 + 1 \text{ (carry)} = 18$
* Result: 187.79

10. 98.145 + 24.21
* Think of 24.21 as 24.210.
* Add thousandths: $5 + 0 = 5$
* Add hundredths: $4 + 1 = 5$
* Add tenths: $1 + 2 = 3$
* Add ones: $8 + 4 = 12$ (write 2, carry 1)
* Add tens: $9 + 2 + 1 \text{ (carry)} = 12$
* Result: 122.355

11. 5.7 + 5.9
* Add tenths: $7 + 9 = 16$ (write 6, carry 1)
* Add ones: $5 + 5 + 1 \text{ (carry)} = 11$
* Result: 11.6

12. 122.37 + 23.48
* Add hundredths: $7 + 8 = 15$ (write 5, carry 1)
* Add tenths: $3 + 4 + 1 \text{ (carry)} = 8$
* Add ones: $2 + 3 = 5$
* Add tens: $2 + 2 = 4$
* Add hundreds: $1 + 0 = 1$
* Result: 145.85

13. 257.17 - 253.59
* Borrow from tenths (1 becomes 0, 7 becomes 17): $17 - 9 = 8$
* Borrow from ones (7 becomes 6, 0 becomes 10): $10 - 5 = 5$
* Subtract ones: $6 - 3 = 3$
* Subtract tens: $5 - 5 = 0$
* Subtract hundreds: $2 - 2 = 0$
* Result: 3.58

14. 69.67 - 67.69
* Borrow from tenths (6 becomes 5, 7 becomes 17): $17 - 9 = 8$
* Borrow from ones (9 becomes 8, 5 becomes 15): $15 - 6 = 9$
* Subtract ones: $8 - 7 = 1$
* Subtract tens: $6 - 6 = 0$
* Result: 1.98

15. 8.27 + 18.97
* Add hundredths: $7 + 7 = 14$ (write 4, carry 1)
* Add tenths: $2 + 9 + 1 \text{ (carry)} = 12$ (write 2, carry 1)
* Add ones: $8 + 8 + 1 \text{ (carry)} = 17$ (write 7, carry 1)
* Add tens: $1 + 1 \text{ (carry)} = 2$
* Result: 27.24

16. 637.9 - 216.6
* Subtract tenths: $9 - 6 = 3$
* Subtract ones: $7 - 6 = 1$
* Subtract tens: $3 - 1 = 2$
* Subtract hundreds: $6 - 2 = 4$
* Result: 421.3

Final Answer:
Left Column:
31.648
33.222
9
2.02
4.4
15.33
0.08
12.16

Right Column:
187.79
122.355
11.6
145.85
3.58
1.98
27.24
421.3