Decimal Operations

Adding Decimals

100

Do you line up decimals when you add?

yes

200

Give directions on how to add these decimals.

1.65 + .23 =

rewrite to line up decimals

bring decimal down

add

300

Add

23.99 + 6.99 = 

30.98

400

Add

204.15  +  1.29

205.44

500

Add

105 + 54.77 =

159.77 

Subtracting Decimals

100

Do you line up decimals when you subtract?

yes

200

Give directions on how to solve

50.00 - 15.25 =

rewrite to line up decimals

bring down decimal 

subtract

300

subtract

9.7 - 0.86 = 

8.84

400

Subtract

75.88 - 3.44 =

72.44

500

subtract

100 - 33.55 =

66.45

Multiplying Decimals

100

Do you line up decimals when you multiply?

no

200

Give directions on how to solve

1. 32 x .2 =

rewrite problem - do not line up decimals

multiply and solve

count decimal spaces and place decimal

300

multiply

3.263 x 1.8 =

5.8734

400

multiply

.325 x .3 =

0.0975

500

multiply

4.65 x .5

2.325

Dividing Decimals

100

Give directions on how to solve

25 / 5

25 is the dividend - in the house

5 is outside the house- the divisor

solve

200

Give directions on how to solve

2.5 / .5

.5- the divisor - move decimal one space to the right

2.5- the dividend- move decimal one space to the right

Place decimal point up

Divide- multiply, subtract, bring it down (repeat if needed)

300

divide

3.66 / .6

6.1

400

divide

56.88 / 8

7.11

500

divide 

125.475 / .15

836.5

Multiply/Divide Powers of Ten

100

423 x 10³ 

423,000

200

600 x 10²

60,000

300

0.004 x 10³

4

400

10 x 10³

10,000

500

5 divided by 10³

0.005