Multiplying Decimals

1
Multiplying Decimals

• Tom Eheman

2
Numbers and Decimals

• Multiply

4 ? 0.17
Step 1 Multiply as you would with whole numbers.
0.17
? 4
68
3
Numbers and Decimals

• Multiply

4 ? 0.17
Step 2 Count the number of decimal places in the
numbers multiplied.
0.17
2 decimal places
? 4
68
4
Numbers and Decimals

• Multiply

4 ? 0.17
Step 3 Place the decimal in the answer with the
number of decimal places from step 2.
0.17
2 decimal places
? 4
68
0.
5
Numbers and Decimals

• Multiply

6 ? 0.32
0.32
Step 1 6 x 32 192
? 6
Step 2 2 Decimal Places
192
.
Step 3 Place Decimal
6
Numbers and Decimals

• Your Turn

7 ? 0.53
0.53
? 7
3.71
7
Decimal by Decimal

• Multiply

0.3 ? 0.4
0.3
0.4
?
12
0.
8
Decimal by Decimal

• Your Turn

2.2 ? 1.4
2.2
1.4
?
3.08
9
Decimal by Decimal

• Additional Example

0.03 ? 0.9
0.03
0.9
?
27
0.0
10
Place The Decimal
4.21
0.09
2.6
7
?
0.5
?
0.3
?
45
0.0
78
0.
2947
.
11
Practice
5 ? 1.4
7.0
3.08 ? 0.7
2.156
0.009
0.3 ? 0.03
26.46
12.6 ? 2.1
12
Science Connection
Weight on Other Planets
Mercury 0.38
Venus 0.9
Moon 0.17
Mars 0.38
Jupiter 2.34
Saturn 1.08
Uranus 0.8
Neptune 1.12
A man weighs 160 pounds on Earth. How much would
he weigh on the moon?
160
0.17
?
1120
1600

2720
.
27.2 lb
13
An oscillating fan spins 1,800 times in 1 minute.
How many times does it spin in 4.5 minutes?
1800
4.5
?
9000
72000

81000
.
8,100 Rotations
14
George earns 7.25 an hour. If he works 8.2 hours
today, how much does he earn?
7.25
8.2
?
1450
58000

59450
.
59.45