Transcript Chapter Four 4.2

Chapter 4
Decimals
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall.
4.2
Order and Rounding
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Comparing Decimals
One way to compare decimals is to compare their graphs on
a number line. Numbers to the left are smaller and numbers
to the right are larger.
Comparing Two Decimals
0
1
0.4
4
10
0.62

62
100
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Comparing Two Decimals
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Example
Insert <, >, or = to form a true statement.
0.645 0.632
The tenths places are the same.
The hundredths places are different.
Since 4 > 3, 0.645 > 0.632
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Example
Write the decimals in order from smallest to largest.
2.007, 3.517, 2.3, 2.03
By comparing the ones digit, the decimal 3.517 is the
largest number. To write the rest of the decimals in
order, we compare digits to the right of the decimal
point. We can insert zeros to help compare.
2.007
2.03
2.3
3.517
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Comparing Decimals
Practice Problems
Problems – insert <, >, or =
Answers
1.
13.208  13.281
2.
3.
4.
0.124  0.086
0.61 
0.076
14.605, 14.65, 13.9, 14.006
13.9 14.006
14.605514.65
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Rounding Decimals
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Example
Round 0.5942 to the nearest thousandth.
Step 1: Locate the digit to the right of the given place value.
0.5942
2 is to the right of the thousandth place value.
Step 2: Since the digit to the right is less than 5, we delete
it and all digits to its right.
Thus 0.5942 rounded to the nearest thousandth is 0.594
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Example
Round $0.067 to the nearest cent.
Step 1: Locate the digit to the right of the given place value.
$0.067
7 is to the right of the hundredths place value
Step 2: Since the digit to the right is more than 5, we
round up.
Thus $0.067 rounds to $0.07.
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Example
An aquarium costs $245.69. Round the price to the
nearest dollar.
The nearest dollar means the ones place. Locate the
digit to the right of the ones place.
$245.69
6 is to the right of the ones place value
Thus $245.69 rounds to $246.00.
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Rounding Decimals
Practice Problems
Problems – insert <, >, or =
Answers
5.
Round 123.7814 to the nearest thousandth.
6.
7.
8.
Round 123.7814 to the nearest tenth
In Citation, the price of a gallon of gasoline is
$2.1589. Round this to the nearest cent.
Round $1.095 to the nearest cent.
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123.781
123.8
$2.16
$1.10
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Rounding Decimals
Practice Problems
Problems – insert <, >, or =
9.
Water bills in Gotham City are always rounded
to the nearest dollar. Lois’s water bill was
$24.62. Round her bill to the nearest dollar.
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Answers
$25
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DONE
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