DECIMALS
Rounding Decimals Review
and
Multiplying Decimals
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Rounding Review
Decimals are read as “and”
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Ten Thousandths
Read as 518 and 21 hundredths
Thousandths
Hundredths
Ones
Tens
Hundreds
Thousands
2 1
___ ___ ___ ___
Tenths
5 1 8
___ , ___ ___ ___
Rounding Review
Find the number. Circle it.
Look next door.
4 or less just ignore.
5 or more add one more.
Example: Round 5368 to nearest hundreds.
Circle the 3 in the hundreds place.
Look next door at the 6.
It is 5 or more so add 1 more to the
hundreds place.
5368 rounds to 5400
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Rounding Review
Round to the
nearest tenths
Round to the
nearest hundredths
2.876
2.9
31.6999
31.70
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Rounding Review
Round to the
nearest tenths
Round to the
nearest hundredths
3.478
3.5
22.5972
22.60
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Multiplying Decimals
Steps for Multiplying Decimals
Step 1:
Step 2:
Write the problem vertically.
Ignore the decimal point(s) and multiply.
Determine where the decimal point
goes in the product.
Step 3:
Place the decimal point in the answer
by counting how many places the
decimal point has moved.
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Multiplying Decimals
Multiply 3 x 0.14
=
0.14
3 x 0.14
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0.42
Multiplying Decimals
Multiply 3 x 0.14
x
1
0.14
Step 1: Write the problem vertically
3
0 42
Step 2: Ignore the decimal points
and multiply
0.42
Step 3: Determine where the decimal
point goes in the product.
The decimal moves two places to the left
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Multiplying Decimals
Multiply 5 x 0.18
=
0.18
5 x 0.18
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0.90
Multiplying Decimals
Multiply 5 x 0.18
x
4
0.18
Step 1: Write the problem vertically
5
0 90
Step 2: Ignore the decimal points
and multiply
0.90
Step 3: Determine where the decimal
point goes in the product.
The decimal moves two places to the left
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Multiplying Decimals
Multiply 0.2 x 0.6
=
0.2
0.6
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0.2
Multiplying Decimals
Multiply 0.2 x 0.6
=
0.2
0.6
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0.2 x 0.6
Multiplying Decimals
Multiply 0.2 x 0.6
=
0.2
0.6
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0.2 x 0.6
= 0.12
Multiplying Decimals
Multiply 0.2 x 0.6
0.2
Step 1: Write the problem vertically
x 0.6
0 12
Step 2: Ignore the decimal points
and multiply
0. 12
Step 3: Determine where the decimal
point goes in the product.
The decimal moves two places to the left
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Multiplying Decimals
Multiply 0.4 x 0.7
=
0.4
0.7
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0.4
Multiplying Decimals
Multiply 0.4 x 0.7
=
0.4
0.7
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0.4 x 0.7
Multiplying Decimals
Multiply 0.4 x 0.7
=
0.4
0.7
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0.28
Multiplying Decimals
Multiply 0.4 x 0.7
0.4
Step 1: Write the problem vertically
x 0.7
0 28
Step 2: Ignore the decimal points
and multiply
0. 28
Step 3: Determine where the decimal
point goes in the product.
The decimal moves two places to the left
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Multiplying Decimals
200
x .25
0
100
+ 4 000
5000
Move the
decimal
two places
to the left in
your answer.
.
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Multiplying Decimals
HOW MANY DECIMAL PLACES?
1) 3.1(0.28)
3.1
 0.28
0.868
1 decimal place
2 decimal places
1 + 2 = 3 decimal places
2) (0.4)(2.53)
0.4
1 decimal place
 2.53
2 decimal places
1.012
1 + 2 = 3 decimal places
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Multiplying Decimals
1
1) 0.16
x 30
0 00
480
480
2)
70
x 1.2
1 40
+7 0 0
840
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21
1
3) 0.0048
x 32
010 9 6
01 440
01 536
Evaluate The Power
An exponent tells how many times a
number is multiplied by itself.
4
Base
3
Exponent
4
3 is written as 3 • 3 • 3 • 3 = 81
This exponent is read three to the fourth power.
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Evaluate The Power
Evaluate (0.2)
2
This means (0.2)(0.2)
0.2
x 0.2
0 04
0. 04
The decimal goes moves two places to the left
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Calculate Area With Decimals
Area = base x height
0.58
in.
4 in.
The decimal
moves two
places to the
left.
Multiply 4 x 0.58
2 3
0.58
x
4
2 32
2.32 in
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2
Area is
square units!
THE END!!!
Take out your study guide
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#5
Multiplying Decimals
1
0.14
x 0.4
Multiply 0.4 x 0.14
Step 1: Write the problem vertically
0 0 56
Step 2: Ignore the decimal points
and multiply
0.056
Step 3: Determine where the decimal
point goes in the product.
The decimal moves 3 places to the left.
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#6
Evaluate The Power
Evaluate (0.5)
2
This means (0.5)(0.5)
The decimal
moves two
places to the left.
2 0.5
x 0.5
0 25
0. 25
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#7
The Area (A) is the number of square units
needed to cover a figure.
Area = base x height
0.98 in
2 in.
The decimal
moves two
places to the
left.
Multiply 2 x 0.98
1 1
0.98
x
2
1 96
1.96 in
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2
Area is
square units!