DECIMALS Rounding Decimals Review and Multiplying Decimals.
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Transcript of DECIMALS Rounding Decimals Review and Multiplying Decimals.
DECIMALSRounding Decimals Review
andMultiplying Decimals
___ , ___ ___ ___ ___ ___ ___ ___
Th
ou
san
ds
Hu
nd
red
s
Ten
s
On
es
Ten
ths
Hu
nd
red
ths
Th
ou
san
dth
s
Ten
Th
ou
san
dth
s
5 1 8 2 1
Read as 518 and 21 hundredths
Decimals are read as “and” Naming Decimals
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
Rounding Review
Round to the nearest tenths
2.876
2.9
Round to the nearest hundredths
31.6999
31.70
Rounding Review
Round to the nearest tenths
3.478
3.5
Round to the nearest hundredths
22.5972
22.60
Rounding Review
Steps for Multiplying Decimals
Step 1: Write the problem vertically.Step 2: Ignore the decimal point(s) and multiply.
Step 3: Determine where the decimal point goes in the product.
Place the decimal point in the answer by counting how many places the decimal point has moved.
Multiplying Decimals
Multiply 3 x 0.14
0.14 3 x 0.14
=
0.42
Multiplying Decimals
Multiply 3 x 0.14
2
Step 1: Write the problem vertically 0.14
x 3 Step 2: Ignore the decimal points and multiply
Step 3: Determine where the decimal point goes in the product.
The decimal moves two places to the left
1
40
0.42
Multiplying Decimals
Multiply 5 x 0.18
0.18 5 x 0.18
=
0.90
Multiplying Decimals
1whole 1whole1whole
Multiply 5 x 0.18
0
Step 1: Write the problem vertically 0.18
x 5 Step 2: Ignore the decimal points and multiply
Step 3: Determine where the decimal point goes in the product.
The decimal moves two places to the left
4
90
0.90
Multiplying Decimals
Multiply 0.2 x 0.6
0.2 0.6
=
0.2
Multiplying Decimals
Multiply 0.2 x 0.6
0.2 0.6
=
0.2 x 0.6
Multiplying Decimals
Multiply 0.2 x 0.6
0.2 0.6
=
0.2 x 0.6= 0.12
Multiplying Decimals
Multiply 0.2 x 0.6
2
Step 1: Write the problem vertically 0.2
x 0.6 Step 2: Ignore the decimal points and multiply
Step 3: Determine where the decimal point goes in the product.
The decimal moves two places to the left
10
0. 12
Multiplying Decimals
Multiply 0.4 x 0.7
0.4 0.7
=
0.4
Multiplying Decimals
Multiply 0.4 x 0.7
0.4 0.7
=
0.4 x 0.7
Multiplying Decimals
copyright©amberpasillas2010
Multiply 0.4 x 0.7
0.4 0.7
=
0.28
Multiplying Decimals
Multiply 0.4 x 0.7
8
Step 1: Write the problem vertically 0.4
x 0.7 Step 2: Ignore the decimal points and multiply
Step 3: Determine where the decimal point goes in the product.
The decimal moves two places to the left
20
0. 28
Multiplying Decimals
Multiplying Decimals200
x .250+
50000
001004
Move the decimal two places
to the left in your answer.
.
Multiplying DecimalsHOW MANY DECIMAL PLACES?
1 decimal place3.1
2) (0.4)(2.53)0.4
2.53
1) 3.1(0.28)
1.012
0.28 2 decimal places0.868 1 + 2 = 3 decimal
places1 decimal place2 decimal places1 + 2 = 3 decimal places
Multiplying Decimals1) 0.16
x 30000084084
12) 70
x 1.2041007048
+
3)
1
0.0048 x 32
690044635
1
1
1
2
0
0
1
0
Evaluate The PowerAn exponent tells how many
times a number is multiplied by itself.
34
BaseExponent
3 is written as 3 • 3 • 3 • 3 = 81 4
This exponent is read three to the fourth power.
Evaluate The PowerEvaluate (0.2)2
4
This means (0.2)(0.2) 0.2
x 0.2
The decimal goes moves two places to the left
00
0. 04
Calculate Area With Decimals
4 in.
0.58 in.
Area = base x height
Multiply 4 x 0.58
2
0.58
x 4
The decimal moves two places to the left.
3
32
2.32 in2
2
Area is square
units!
Review
Multiply 0.4 x 0.14
6
Step 1: Write the problem vertically 0.14
x 0.4Step 2: Ignore the decimal points and multiply
Step 3: Determine where the decimal point goes in the product.
The decimal moves 3 places to the left.
1
50
0.056
Multiplying Decimals#5
0
Evaluate (0.5)2
5
This means (0.5)(0.5) 0.5
x 0.5The decimal moves two
places to the left.
20
0. 25
#6
2
2 in.
0.98 in Area = base x height
# 7
Multiply 2 x 0.98
6
0.98x 2
The decimal moves two places to the left.
1
91
1.96 in2
1
Area is square
units!
The Area (A) is the number of square units needed to cover a figure.