1. Chapter 15 Decimals: Addition and Subtraction
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2. Lesson 15-1 Round Decimals
Decimals: Addition and Subtraction 15
Lesson Round Decimals
Lesson Estimate Decimal Sums and Differences
Lesson Problem-Solving Strategy: Work Backward
Lesson Add Decimals
Lesson Problem-Solving Investigation: Choose a Strategy
Lesson Subtract Decimals
Chapter Menu

3. Five-Minute Check (over Chapter 14) Main Idea and Vocabulary
15-1
Round Decimals
Five-Minute Check (over Chapter 14)
Main Idea and Vocabulary
California Standards
Example 1: Round Decimals
Example 2: Round Decimals
Example 3: Round Decimals
Lesson 1 Menu

4. I will round decimals. decimal decimal point 15-1 Round Decimals
Lesson 1 MI/Vocab

5. 15-1
Round Decimals
Standard 4NS2.2 Round two-place decimals to one decimal or the nearest whole number and judge the reasonableness of the rounded answer.
Lesson 1 Standard 1

6. 15-1
Round Decimals
About 2.93 million people live in San Diego County, California. How many people live in San Diego County when rounded to the nearest whole number?
Lesson 1 Ex1

7. One Way: Use a Number Line
15-1
Round Decimals
One Way: Use a Number Line
2.93 is between 2 and 3.
It is closer to 3.
So, round 2.93 to 3.
Lesson 1 Ex1

8. Another Way: Use Rounding Rules
15-1
Round Decimals
Another Way: Use Rounding Rules
Use the same process that you use with rounding whole numbers.
2.93
Lesson 1 Ex1

9. 15-1
Round Decimals
Answer: To the nearest whole number, rounds to 3. About 3 million people live in San Diego County, California.
Lesson 1 Ex1

10. Round 4.65 to the nearest whole number.
15-1
Round Decimals
Round 4.65 to the nearest whole number. 3 4 5 6
Lesson 1 CYP1

11. Round 46.45 to the nearest whole number.
15-1
Round Decimals
Round to the nearest whole number.
Use the rounding rules.
46.45
Answer: To the nearest whole number, rounds to 46.
Lesson 1 Ex2

12. Round 87.38 to the nearest whole number.
15-1
Round Decimals
Round to the nearest whole number. 89 88 87 86
Lesson 1 CYP2

13. Answer: To the nearest tenth, 72.84 rounds to 72.8.
15-1
Round Decimals
A golfer had an average score of in one season. Round this score to the nearest tenth.
Use the rounding rules.
72.84
Answer: To the nearest tenth, rounds to 72.8.
Lesson 1 Ex3

14. Round 92.37 to the nearest tenth.
15-1
Round Decimals
Round to the nearest tenth.
92.2
92.3
92.4
92.5
Lesson 1 CYP3

15. End of Lesson 1

16. Five-Minute Check (over Lesson 15-1) Main Idea and Vocabulary
15-2
Estimate Decimal Sums and Differences
Five-Minute Check (over Lesson 15-1)
Main Idea and Vocabulary
California Standards
Key Concept: Estimate Decimal Sums
Key Concept: Estimate Decimal Differences
Example 1: Estimate Sums
Example 2: Estimate Differences
Lesson 2 Menu

17. I will use rounding to estimate sums and differences.
15-2
Estimate Decimal Sums and Differences
I will use rounding to estimate sums and differences.
estimate
Lesson 2 MI/Vocab

18. 15-2
Estimate Decimal Sums and Differences
Standard 4NS2.1 Estimate and compute the sum or difference of whole numbers and positive decimals to two places.
Lesson 2 Standard 1

19. 15-2
Estimate Decimal Sums and Differences
Lesson 2 Key Concept 1

20. 15-2
Estimate Decimal Sums and Differences
Lesson 2 Key Concept 2

21. Answer: So, Belkis rode her bike about 11 miles.
15-2
Estimate Decimal Sums and Differences
Belkis rides her bike 4.6 miles on Saturday and 6.25 miles on Sunday. About how many miles does she ride her bike altogether on both days?
You need to estimate Round each addend to the nearest whole number. Then add.
Round 4.6 to 5.
Round 6.25 to 6.
6.25 +
4.6 5 + 6 11
Answer: So, Belkis rode her bike about 11 miles.
Lesson 2 Ex1

22. 15-2
Estimate Decimal Sums and Differences
Adriano ran 2.3 miles on Friday and 3.45 miles on Saturday. About how many miles did he run altogether on both days? 3 4 5 6
Lesson 2 CYP1

23. 15-2
Estimate Decimal Sums and Differences
Jairo has $ If he buys a CD that costs $16.99, about how much money will he have left?
You need to estimate $38.55 – $ Round each decimal to the nearest whole number. Then subtract.
Lesson 2 Ex2

24. Answer: So, Jairo will have about $22 left.
15-2
Estimate Decimal Sums and Differences
Round $38.55 to $39.
Round $16.99 to $17.
$38.55
$16.99 –
$39
$17 –
$39
$17 –
$22
Answer: So, Jairo will have about $22 left.
Lesson 2 Ex2

25. 15-2
Estimate Decimal Sums and Differences
Sonia has $ If she buys a pair of shoes for $24.99, about how much money will she have left?
$18
$19
$20
$21
Lesson 2 CYP2

26. End of Lesson 2

27. Five-Minute Check (over Lesson 15-2) Main Idea California Standards
15-3
Problem-Solving Strategy: Work Backward
Five-Minute Check (over Lesson 15-2)
Main Idea
California Standards
Example 1: Problem-Solving Strategy
Lesson 3 Menu

28. I will solve problems by working backward.
15-3
Problem-Solving Strategy: Work Backward
I will solve problems by working backward.
Lesson 3 MI/Vocab

29. 15-3
Problem-Solving Strategy: Work Backward
Standard 4MR1.1 Analyze problems by identifying relationships, distinguishing relevant from irrelevant information, sequencing and prioritizing information, and observing patterns.
Lesson 3 Standard 1

30. 15-3
Problem-Solving Strategy: Work Backward
Standard 4NS3.1 Demonstrate an understanding of, and the ability to use, standard algorithms for the addition and subtraction of multidigit numbers.
Lesson 3 Standard 2

31. 15-3
Problem-Solving Strategy: Work Backward
Rey has lacrosse practice in the evenings. He gets home from school and eats a snack for 15 minutes. Then he spends 1 hour doing his homework. It takes him 15 minutes to get to practice. Practice is at 5 P.M. What time does Rey get home from school?
Lesson 3 Ex1

32. Understand What facts do you know? Rey eats a snack for 15 minutes.
15-3
Problem-Solving Strategy: Work Backward
Understand
What facts do you know?
Rey eats a snack for 15 minutes.
He works on homework for 1 hour.
It takes 15 minutes to get to practice at 5 P.M.
What do you need to find?
What time Rey gets home from school.
Lesson 3 Ex1

33. Plan Work backward to solve the problem. 15-3
Problem-Solving Strategy: Work Backward
Plan
Work backward to solve the problem.
Lesson 3 Ex1

34. 15-3
Problem-Solving Strategy: Work Backward
Solve
Start with the end result. Then work backward one step at a time.
5 P.M. – 15 minutes = 4:45 P.M.
practice starts
time to get to practice
4:45 P.M. – 1 hour = 3:45 P.M.
time spent on homework
Lesson 3 Ex1

35. Solve 3:45 P.M. – 15 minutes = 3:30 P.M.
15-3
Problem-Solving Strategy: Work Backward
Solve
3:45 P.M. – 15 minutes = 3:30 P.M.
time spent eating
Answer: So, Rey gets home from school at 3:30 P.M.
Lesson 3 Ex1

36. Check Look back at the problem.
15-3
Problem-Solving Strategy: Work Backward
Check
Look back at the problem.
hour + 15 minutes = 1 hour and 30 minutes
If he gets home at 3:30 P.M., one hour and 30 minutes later would be 5 P.M.
The answer is correct.
Lesson 3 Ex1

37. End of Lesson 3

38. Five-Minute Check (over Lesson 15-3) Main Idea California Standards
15-4
Add Decimals
Five-Minute Check (over Lesson 15-3)
Main Idea
California Standards
Example 1: Add Decimals
Example 2: Add Decimals
Addition of Decimals
Lesson 4 Menu

39. 15-4
Add Decimals
I will add decimals.
Lesson 4 MI/Vocab

40. 15-4
Add Decimals
Standard 4NS2.1 Estimate and compute the sum or difference of whole numbers and positive decimals to two places.
Standard 4MR2.1 Use estimation to verify the reasonableness of calculated results.
Lesson 4 Standard 1

41. Step 1 Line up the decimal points.
15-4
Add Decimals
Odina slept 8.3 hours on Monday night and hours on Tuesday night. How many hours did she sleep on the two nights combined?
Estimate = 16
Step 1 Line up the decimal points.
Write a 0 in the hundredths place as a placeholder.
8.30 +
7.66
Lesson 4 Ex1

42. Answer: So, Odina slept a total of 15.96 hours.
15-4
Add Decimals
Step 2 Add.
Add the digits in each place value. Then bring down the decimal point.
8.30
7.66 +
15.96
Answer: So, Odina slept a total of hours.
Lesson 4 Ex1

43. Check for Reasonableness
15-4
Add Decimals
Check for Reasonableness
Since is close to the estimate of 16, the answer is reasonable.
Lesson 4 Ex1

44. 15-4
Add Decimals
Meredith studied for 2.4 hours on Tuesday night and 1.83 hours on Wednesday night. How many hours did she spend studying on the two nights combined?
3.23 hours
4.23 hours
4.33 hours
5.23 hours
Lesson 4 CYP1

45. Step 1 Line up the decimal points.
15-4
Add Decimals
Kate spent $1.25 for a juice box and $1.79 for yogurt. How much did she spend in all?
You need to find $ $1.79.
Estimate $1 + $2 = $3
Step 1 Line up the decimal points.
$1.25 +
$1.79
Lesson 4 Ex2

46. Step 2 Add. $1.25 $1.79 + $3. 4 Answer: So, Kate spent $3.04. 15-4
Add Decimals
Step 2 Add. 1 1
$1.25
$1.79 +
Add the digits in each place value. Regroup if necessary.
$3. 4
Answer: So, Kate spent $3.04.
Lesson 4 Ex2

47. Check for Reasonableness
15-4
Add Decimals
Check for Reasonableness
The sum of $3.04 is close to the estimate of 3, so the answer is reasonable.
Lesson 4 Ex2

48. 15-4
Add Decimals
Jerome spent $2.55 on a sandwich and $1.75 on a bottle of juice. How much did he spend in all?
$3.20
$4.20
$4.30
$4.75
Lesson 4 CYP2

49. End of Lesson 4

50. Five-Minute Check (over Lesson 15-4) Main Idea California Standards
15-5
Problem-Solving Investigation: Choose a Strategy
Five-Minute Check (over Lesson 15-4)
Main Idea
California Standards
Example 1: Problem-Solving Investigation
Lesson 5 Menu

51. I will choose the best strategy to solve a problem.
15-5
Problem-Solving Investigation: Choose a Strategy
I will choose the best strategy to solve a problem.
Lesson 5 MI/Vocab

52. 15-5
Problem-Solving Investigation: Choose a Strategy
Standard 4MR1.1 Analyze problems by identifying relationships, distinguishing relevant from irrelevant information, sequencing and prioritizing information, and observing patterns.
Lesson 5 Standard 1

53. 15-5
Problem-Solving Investigation: Choose a Strategy
Standard 4SDAP1.1 Formulate survey questions; systematically collect and represent data on a number line; and coordinate graphs, tables, and charts.
Lesson 5 Standard 2

54. YOUR MISSION: Find with person owns each pet.
15-5
Problem-Solving Investigation: Choose a Strategy
JENNIFER: My friends and I have pets. We all have different kinds of pets. Among the three of us, we have a lizard, a cat, a gerbil, and a snake. I do not have a cat. Rondell’s pet is not a gerbil or a snake. Lorena’s two pets are not lizards. My pet does not begin with the letters s or g.
YOUR MISSION: Find with person owns each pet.
Lesson 5 Ex1

55. Understand What facts do you know?
15-5
Problem-Solving Investigation: Choose a Strategy
Understand
What facts do you know?
You know the clues for each person’s pet.
What do you need to find?
You need to find which person owns each pet.
Lesson 5 Ex1

56. 15-5
Problem-Solving Investigation: Choose a Strategy
Plan
Make a table to show what you know. Then use logical reasoning to find which person owns each pet.
Lesson 5 Ex1

57. 15-5
Problem-Solving Investigation: Choose a Strategy
Solve
Make a table. Write a yes or no for each fact that you are given. Once you write yes in the table, you can write no in the rest of the boxes in that row and column.
Lesson 5 Ex1

58. 15-5
Problem-Solving Investigation: Choose a Strategy
Solve
Answer: So, Jennifer owns a lizard. Lorena owns a gerbil and a snake. Rondell owns a cat.
Lesson 5 Ex1

59. 15-5
Problem-Solving Investigation: Choose a Strategy
Check
Look back at the problem. The solution matches the facts given in the problem. So, the answer is correct.
Lesson 5 Ex1

60. End of Lesson 5

61. Subtraction of Decimals
15-6
Subtract Decimals
Five-Minute Check (over Lesson 15-5)
Main Idea
California Standards
Example 1: Subtract Decimals
Example 2: Subtract Decimals
Subtraction of Decimals
Lesson 6 Menu

62. I will subtract decimals.
15-6
Subtract Decimals
I will subtract decimals.
Lesson 6 MI/Vocab

63. 15-6
Subtract Decimals
Standard 4NS2.1 Estimate and compute the sum or difference of whole numbers and positive decimals to two places.
Standard 4MR2.1 Use estimation to verify reasonableness of calculated results.
Lesson 6 Standard 1

64. Step 1 Line up the decimal points.
15-6
Subtract Decimals
A fruit stand sells a bag of grapes for $1.70 and a bunch of bananas for $1.19. What is the difference in price?
Estimate $1.70 – $ $1.7 – $1.2 = $0.50
Step 1 Line up the decimal points.
$1.70 –
$1.19
Lesson 6 Ex1

65. Step 2 Subtract. Regroup if needed.
15-6
Subtract Decimals
Step 2 Subtract. Regroup if needed. 6 10
$1.70
$1.19 –
Place the decimal point.
$0. 5 1
Answer: So, the difference in price is $0.51.
Lesson 6 Ex1

66. Check for Reasonableness
15-6
Subtract Decimals
Check for Reasonableness
Since the answer of $0.51 is close to the estimate of $0.50, the answer is reasonable.
Lesson 6 Ex1

67. Find the difference between 2.25 and 1.4.
15-6
Subtract Decimals
Find the difference between 2.25 and 1.4.
1.85
0.85
0.05
0.80
Lesson 6 CYP1

68. Step 1 Line up the decimal points.
15-6
Subtract Decimals
Arati is 52.5 inches tall and her sister is 48.8 inches tall. How much taller is Arati than her sister?
Estimate – – 49 = 4
Step 1 Line up the decimal points.
52.5 –
48.8
Lesson 6 Ex2

69. Answer: So, Arati is 3.7 inches taller than her sister.
15-6
Subtract Decimals
Step 2 Subtract. 11 4 1 15
Subtract the digits in each place value. Regroup if necessary.
52.5
48.8 – 3. 7
Answer: So, Arati is 3.7 inches taller than her sister.
Lesson 6 Ex2

70. Check for Reasonableness
15-6
Subtract Decimals
Check for Reasonableness
The answer 3.7 is close to the estimate of 4. So, the answer is reasonable.
Lesson 6 Ex2

71. Find the difference between 78.2 and 55.1.
15-6
Subtract Decimals
Find the difference between 78.2 and 55.1.
231
2.31
23.1
0.231
Lesson 6 CYP2

72. End of Lesson 6

73. 15 Five-Minute Checks Math Tool Chest Image Bank Addition of Decimals
Decimals: Addition and Subtraction 15
Five-Minute Checks
Math Tool Chest
Image Bank
Addition of Decimals
Subtraction of Decimals
CR Menu

74. 1. Exit this presentation.
To use the images that are on the following four slides in your own presentation:
1. Exit this presentation.
2. Open a chapter presentation using a full installation of Microsoft® PowerPoint® in editing mode and scroll to the Image Bank slides.
3. Select an image, copy it, and paste it into your presentation.
IB Instructions

75. IB 1

76. IB 2

77. IB 3

78. IB 4

79. Lesson 15-1 (over Chapter 14) Lesson 15-2 (over Lesson 15-1)
Decimals: Addition and Subtraction 15
Lesson 15-1 (over Chapter 14)
Lesson 15-2 (over Lesson 15-1)
Lesson 15-3 (over Lesson 15-2)
Lesson 15-4 (over Lesson 15-3)
Lesson 15-5 (over Lesson 15-4)
Lesson 15-6 (over Lesson 15-5)
5Min Menu

80. Compare. Write <, >, or =.
(over Chapter 14)
Compare. Write <, >, or =. 3 10
<
> =
5Min 1-1

81. Compare. Write <, >, or =.
(over Chapter 14)
Compare. Write <, >, or =.
<
> =
5Min 1-2

82. Compare. Write <, >, or =.
(over Chapter 14)
Compare. Write <, >, or =. 1 10
<
> =
5Min 1-3

83. Compare. Write <, >, or =.
(over Chapter 14)
Compare. Write <, >, or =.
<
> =
5Min 1-4

84. Use a number line to order from greatest to least.
(over Chapter 14)
Use a number line to order from greatest to least.
11 , 11.9, , 11.25 38
100 1 2
A , 11.25, , 11 38
100 1 2
B , 11.9, 11.25, 11 38
100 1 2
C , , , 11.25 38
100 1 2
D , 11.9, , 11.25 38
100 1 2
5Min 1-5

85. Use a number line to order from greatest to least.
(over Chapter 14)
Use a number line to order from greatest to least.
3 , 4.62, 3.2, 4 4 5 10
A , 3 , , 4.62 4 5 10
B , 4.62, 3 , 3.2 4 5 10
C , , 3.2, 3 4 5 10
D , , 3 , 3.2 4 5 10
5Min 1-6

86. Round 1.43 to the nearest whole number.
(over Lesson 15-1)
Round 1.43 to the nearest whole number.
1.5 1 2
5Min 2-1

87. Round 26.72 to the nearest whole number.
(over Lesson 15-1)
Round to the nearest whole number. 26 20 27 30
5Min 2-2

88. Round 53.54 to the nearest whole number.
(over Lesson 15-1)
Round to the nearest whole number. 53 50
53.5 54
5Min 2-3

89. Round 67.15 to the nearest whole number.
(over Lesson 15-1)
Round to the nearest whole number. 67 70 60 68
5Min 2-4

90. Round 3.16 to the nearest tenth.
(over Lesson 15-1)
Round 3.16 to the nearest tenth.
3.1 3
3.2
5Min 2-5

91. Round 9.35 to the nearest tenth.
(over Lesson 15-1)
Round 9.35 to the nearest tenth.
9.3 9
9.4 10
5Min 2-6

92. Round 48.51 to the nearest tenth.
(over Lesson 15-1)
Round to the nearest tenth. 49
48.5 48
48.1
5Min 2-7

93. Round 92.64 to the nearest tenth.
(over Lesson 15-1)
Round to the nearest tenth.
92.7 93
92.1
92.6
5Min 2-8

94. Estimate. Round to the nearest whole number.
(over Lesson 15-2)
Estimate. Round to the nearest whole number. 4
4.5 5
4.9
5Min 3-1

95. Estimate. Round to the nearest whole number.
(over Lesson 15-2)
Estimate. Round to the nearest whole number. 49
50.5 50 51
5Min 3-2

96. Estimate. Round to the nearest whole number.
(over Lesson 15-2)
Estimate. Round to the nearest whole number.
– 8.27 21 38 22
20.8
5Min 3-3

97. Estimate. Round to the nearest whole number.
(over Lesson 15-2)
Estimate. Round to the nearest whole number.
66.3 – 19.51
47.7 45 46
46.8
5Min 3-4

98. Estimate. Round to the nearest whole number.
(over Lesson 15-2)
Estimate. Round to the nearest whole number. 19
19.6 20
15.2
5Min 3-5

99. Estimate. Round to the nearest whole number.
(over Lesson 15-2)
Estimate. Round to the nearest whole number. 52 53
52.6 51
5Min 3-6

100. Estimate. Round to the nearest whole number.
(over Lesson 15-2)
Estimate. Round to the nearest whole number.
$52.25 – $44.77
$8.00
$7.50
$12.52
$7.00
5Min 3-7

101. (over Lesson 15-3)
Solve. Use the work backward strategy. A number is added to 2. Next, the sum is divided by 3. Then, 1 is subtracted from the quotient. The result is 3. What is the number? 2 7 10 12
5Min 4-1

102. Add. Use estimation to check for reasonableness.
(over Lesson 15-4)
Add. Use estimation to check for reasonableness.
0.12 12
1.2
1.4
5Min 5-1

103. Add. Use estimation to check for reasonableness.
(over Lesson 15-4)
Add. Use estimation to check for reasonableness.
9.6
10.66
9.12
9.66
5Min 5-2

104. Add. Use estimation to check for reasonableness.
(over Lesson 15-4)
Add. Use estimation to check for reasonableness.
12.72
13.82
11.82
13.72
5Min 5-3

105. Add. Use estimation to check for reasonableness.
(over Lesson 15-4)
Add. Use estimation to check for reasonableness.
$ $6.89
$13.96
$12.86
$12.96
$12.97
5Min 5-4

106. Add. Use estimation to check for reasonableness.
(over Lesson 15-4)
Add. Use estimation to check for reasonableness.
58.30
68.30
58.29
57.20
5Min 5-5

107. Add. Use estimation to check for reasonableness.
(over Lesson 15-4)
Add. Use estimation to check for reasonableness.
85.90
74.81
75.91
84.91
5Min 5-6

108. Add. Use estimation to check for reasonableness.
(over Lesson 15-4)
Add. Use estimation to check for reasonableness.
$ $19.52
$71.02
$82.02
$82.12
$81.02
5Min 5-7

109. Add. Use estimation to check for reasonableness.
(over Lesson 15-4)
Add. Use estimation to check for reasonableness.
8.82
3.05
8.92
4.15
5Min 5-8

110. Finn: red; Malik: blue; Kwag: green
(over Lesson 15-5)
Use any problem-solving strategy to solve. Finn, Malik, and Kwag are all wearing different colored shirts. Their shirts are red, blue, or green. Malik’s shirt is not blue. Finn’s shirt color doesn’t start with an r or a g. Kwag’s shirt is green. What color shirt is each boy wearing?
Finn: red; Malik: blue; Kwag: green
Finn: blue; Malik: green; Kwag: red
Finn: yellow; Malik: red; Kwag: green
Finn: blue; Malik: red; Kwag: green
5Min 6-1

111. This slide is intentionally blank.
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