Decimals: Addition and Subtraction

Decimal Addition

100

0.5 + 0.3

0.8

200

2.4 + 1.7

4.1

300

3.25 + 0.6

3.85

400

5.08 + 2.9

7.98

500

7.456 + 2.34

9.796

Decimal Subtraction

100

0.9 - 0.4

0.5

200

3.5 - 1.2

2.3

300

6.0 - 2.75

3.25

400

8.4 - 3.86

4.54

500

10.00 - 4.678

5.322

Mixed

100

4.2 + 1.3 

5.5

200

6.5 - 2.1

4.4

300

3.75 + 2.4

6.15

400

9.0 - 3.68

5.32

500

5.46 + 1.275

6.735

Tricky Questions

100

2.5 + 0.75

3.25 -> Trick: line up decimals, don’t just add 25 + 75 

200

4 - 2.6

1.4 -> (Trick: write 4 as 4.0) 

300

3.2 + 1.08

4.28 -> (Trick: add a zero → 3.20 + 1.08) 

400

5.00 - 2.75 

2.25 -> (Trick: Borrow the ones place -> 5 -> 4.10 -> 4.910 ->

Hundredths: 10 − 5 = 5

Tenths: 9 − 7 = 2

Ones: 4 − 2 = 2

=2.25

500

0.9 + 0.35

1.25 -> (Trick: regrouping when decimals add past 1)