Transcript Chapter 1, Section 1

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Sec 5.5 - 1
5.5 Dividing Signed
Decimal Numbers
Chapter 5
Rational Numbers: Positive and
Negative Decimals
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Sec 5.5 - 2
5.5 Dividing Signed Decimal Numbers
Objectives
1.
Divide a decimal by an integer.
2.
Divide a number by a decimal.
3.
Estimate the answer when dividing decimals.
4.
Use the order of operations with decimals.
Copyright © 2010 Pearson Education, Inc. All rights reserved.
Sec 5.5 - 3
Objective 1: Divide a decimal by an integer.
Copyright © 2010 Pearson Education, Inc. All rights reserved.
Sec 5.5 - 4
Objective 1: Divide a decimal by an integer.
Example Find the quotient 21.93 ÷ (–3).
First consider 21.93 ÷ 3.
Step 1
Write the decimal point in the quotient directly
above the decimal point in the dividend.
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Sec 5.5 - 5
Objective 1: Divide a decimal by an integer.
Example (continued)
Step 2
Divide as if the numbers were whole numbers.
Check by multiplying the quotient times the divisor.
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Sec 5.5 - 6
Objective 1: Divide a decimal by an integer.
Example (continued)
Step 3
The quotient is –7.31 because the numbers have
different signs.
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Sec 5.5 - 7
Objective 1: Divide a decimal by an integer.
Example Find the quotient 470.7 ÷ 9.
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Sec 5.5 - 8
Objective 1: Divide a decimal by an integer.
Example Divide 1.5 by 8. Use multiplying to
check the quotient.
Keep dividing until the remainder is 0, or until the
digits in the quotient begin to repeat in a pattern. If
you run out of digits in the dividend, write extra
zeros on the right side of the dividend so you can
continue dividing.
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Sec 5.5 - 9
Objective 1: Divide a decimal by an integer.
Example (continued)
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Sec 5.5 - 10
Objective 1: Divide a decimal by an integer.
Example Divide 4.7 by 3. Round to the nearest
thousandth.
Write extra zeros
in the dividend so
that you can
continue dividing.
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Sec 5.5 - 11
Objective 1: Divide a decimal by an integer.
Example (continued)
The digit 6 in the quotient is repeating and will
continue to do so. The remainder will never be 0.
The quotient is a repeating decimal that goes on
forever. We may write the quotient in two ways.
or
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Sec 5.5 - 12
Objective 1: Divide a decimal by an integer.
Example (continued)
Check the answer by multiplying 1.567 by 3.
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Sec 5.5 - 13
Objective 2: Divide a number by a decimal.
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Sec 5.5 - 14
Objective 2: Divide a number by a decimal.
Example Divide
.
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Sec 5.5 - 15
Objective 2: Divide a number by a decimal.
Example Divide –5 by –4.2. Round to the nearest
hundredth.
First consider
.
Move the decimal point in
the divisor one place to the
right so that becomes the
whole number 42. The
decimal point in the
dividend is also moved one
place to the right.
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Sec 5.5 - 16
Objective 2: Divide a number by a decimal.
Example (continued)
Rounding the quotient to the nearest hundredth
gives 1.19.
The quotient is positive because both the divisor
and dividend have the same sign.
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Sec 5.5 - 17
Objective 3: Estimate the answer when
dividing by decimals.
Example Suppose a student was asked to
estimate the quotient 580.44 ÷ 2.8 using front end
rounding and then find the exact answer. Find the
error in the student’s solution that follows.
The exact answer should be 207.3.
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Sec 5.5 - 18
Objective 4: Use the order of operations with
decimals.
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Sec 5.5 - 19
Objective 4: Use the order of operations with
decimals.
Example Simplify
order of operations.
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using the
Sec 5.5 - 20
Objective 4: Use the order of operations with
decimals.
Example Simplify
order of operations.
Copyright © 2010 Pearson Education, Inc. All rights reserved.
using the
Sec 5.5 - 21
Objective 4: Use the order of operations with
decimals.
Example Simplify
order of operations.
Copyright © 2010 Pearson Education, Inc. All rights reserved.
using the
Sec 5.5 - 22