PowerPoint Presentation by Charlie CookThe University of West Alabama

PowerPoint Presentation by Charlie CookThe University of West Alabama

© 2009 Cengage Learning. All rights reserved.© 2009 Cengage Learning. All rights reserved.

DecimalsUEI College

CHAPTER 3

© 2009 Cengage Learning. All rights reserved. 3–2

PERFORMANCE OBJECTIVESPERFORMANCE OBJECTIVESPERFORMANCE OBJECTIVESPERFORMANCE OBJECTIVES

Section I Understanding Decimal Numbers

3-1: Reading and writing decimal numbers in numerical and word form

3-2: Rounding decimal numbers to a specified place value

Section II Decimal Numbers and the Fundamental Processes

3-3: Adding and subtracting decimals

3-4: Multiplying decimals

3-5: Dividing decimals

Section III Conversion of Decimals to Fractions and Fractions to Decimals

3-6: Converting decimals to fractions

3-7: Converting fractions to decimals

© 2009 Cengage Learning. All rights reserved. 3–3

Understanding Decimal Numbers Understanding Decimal Numbers (Page 68)(Page 68)

• Decimal numbers, or decimalsDecimal numbers, or decimals Amounts less than whole, or less than one. Amounts less than whole, or less than one. For example, For example, .44.44 is a decimal number. is a decimal number.

• Decimal pointDecimal point A dot written in a decimal number to indicate where A dot written in a decimal number to indicate where

the place values change from whole numbers to the place values change from whole numbers to decimal numbers.decimal numbers.

• Mixed decimalsMixed decimals Decimals written in conjunction with whole numbers.Decimals written in conjunction with whole numbers. For example, For example, 2.442.44 is a mixed decimal. is a mixed decimal.

© 2009 Cengage Learning. All rights reserved. 3–4

Exhibit 3-1 Decimal Numbers Place Value Chart (Page 69)

© 2009 Cengage Learning. All rights reserved. 3–5

Reading and Writing DecimalsReading and Writing Decimals

• Step 1:Step 1: Read or write the decimal part as if itRead or write the decimal part as if itwere a whole numberwere a whole number

• Step 2: Name the place value of the last digitStep 2: Name the place value of the last digiton the righton the right

• Note:Note: The word “and” is used to representThe word “and” is used to representthe decimal point.the decimal point.

© 2009 Cengage Learning. All rights reserved. 3–6

Writing Decimals Example (Page 69)Writing Decimals Example (Page 69)

• Write the following decimal numbers in Write the following decimal numbers in numerical form:numerical form: .25.25

twenty-five hundredthstwenty-five hundredths .00034.00034

thirty-four hundred thousandthsthirty-four hundred thousandths 15.90115.901

fifteen and nine hundred one thousandthsfifteen and nine hundred one thousandths

© 2009 Cengage Learning. All rights reserved. 3–7

Rounding Decimal Numbers Rounding Decimal Numbers to a Specified Place Value (Page 71)to a Specified Place Value (Page 71)

© 2009 Cengage Learning. All rights reserved. 3–8

Rounding Decimal Numbers ExampleRounding Decimal Numbers Example

• Round the following numbers to the place underlined:Round the following numbers to the place underlined:

.0.08833

.08.08

.14.14557878

.146.146

234.234.33627627

234.4234.4

.777.7777777

.7778.7778

© 2009 Cengage Learning. All rights reserved. 3–9

Adding and Subtracting DecimalsAdding and Subtracting Decimals

© 2009 Cengage Learning. All rights reserved. 3–10

Adding Decimal Numbers (Page 74)Adding Decimal Numbers (Page 74)

241.89 + 11.9 + .0344

241.890011.9000+ .0344

253.8244

.09 + .099 + .0999

.09 .099+.0999 .2889

© 2009 Cengage Learning. All rights reserved. 3–11

Subtracting Decimal Numbers (Page Subtracting Decimal Numbers (Page 74) 74)

65.987–15.9873

65.9870-15.9873 49.9997

1.004-.35

1.004-.350.654

© 2009 Cengage Learning. All rights reserved. 3–12

Multiplying Decimals (Page 75)Multiplying Decimals (Page 75)

© 2009 Cengage Learning. All rights reserved. 3–13

Multiplying DecimalsMultiplying Decimals

19.02.242

9838.45

020224

217818

19.

02.242

2.0003.

00006.

2.0003.

© 2009 Cengage Learning. All rights reserved. 3–14

Multiplication Shortcut (Page 75)Multiplication Shortcut (Page 75)

• Whenever you are multiplying a decimal by a power of 10, Whenever you are multiplying a decimal by a power of 10, such as 10, 100, 1,000, 10,000, etc., count the number of such as 10, 100, 1,000, 10,000, etc., count the number of zeros in the multiplier and move the decimal point in the zeros in the multiplier and move the decimal point in the multiplicand the same number of places to the right. multiplicand the same number of places to the right.

• If necessary, add zeros to the product to provide the If necessary, add zeros to the product to provide the required places.required places.

546710067.547.5461067.54

© 2009 Cengage Learning. All rights reserved. 3–15

Dividing Decimals (Page 76)Dividing Decimals (Page 76)

0201201

08

46.2.920202.9

0612

2.6.1263636.12

© 2009 Cengage Learning. All rights reserved. 3–16

PART IIPART II

© 2009 Cengage Learning. All rights reserved. 3–17

Dividing Decimals (cont’d)Dividing Decimals (cont’d)

© 2009 Cengage Learning. All rights reserved. 3–18

Dividing Decimals ExamplesDividing Decimals Examples

011211216

17272162.276.1 6.12.27

7.5.3

035

53575.37.

© 2009 Cengage Learning. All rights reserved. 3–19

Division Shortcut (Page 77)Division Shortcut (Page 77)

• Whenever you divide a decimal by a power of 10, such Whenever you divide a decimal by a power of 10, such as 10, 100, 1,000, 10,000, etc., count the number of as 10, 100, 1,000, 10,000, etc., count the number of zeros in the divisor and move the decimal point in the zeros in the divisor and move the decimal point in the dividend the same number of places to the left. dividend the same number of places to the left.

• It may be necessary to add zeros to provide the required It may be necessary to add zeros to provide the required places.places.

467.51067.54

5467.10067.54

05467.100067.54

© 2009 Cengage Learning. All rights reserved. 3–20

Converting Decimals to Fractions Converting Decimals to Fractions (Page 83)(Page 83)

10049

49. 1258

000,164

064.

© 2009 Cengage Learning. All rights reserved. 3–21

Converting Fractions to DecimalsConverting Fractions to Decimals (Page 84) (Page 84)

0

02

4.0.25

52

1910901

15

33.500.163

316

© 2009 Cengage Learning. All rights reserved. 3–22

Chapter Review Problem 1Chapter Review Problem 1

• Marlene’s Rebollar Monthly overtime was 26 hours. Marlene’s Rebollar Monthly overtime was 26 hours. What was the average number of overtime hours per What was the average number of overtime hours per week did she work?week did she work?

00202

24

5.60.264

426

© 2009 Cengage Learning. All rights reserved. 3–23

Chapter Review Problem 2Chapter Review Problem 2

• Overtime costs the company $15.50 per hour.Overtime costs the company $15.50 per hour.• If total Juanita Del Cid overtime was 26 hours If total Juanita Del Cid overtime was 26 hours

last month, what was the cost to the company last month, what was the cost to the company for her overtime?for her overtime?

00.403

3100

0093

26

50.15