1. Warm Up
Problem of the Day
Lesson Presentation
Lesson Quizzes

2. Warm Up
Divide.
÷ 2
÷ 7
÷ 3
÷ 4
2.4
2.3
0.12
6.32

3. Problem of the Day
In the following magic square, is the product of the numbers in every row, column, and diagonal. Fill in the missing numbers.
4.5
0.25
0.5 3 1
1.5
2.25
0.75 9

4. Learn to divide whole numbers and decimals by decimals.

5. Multiplying the divisor and the dividend by the same number does not change the quotient.
42 ÷ 6 = 7
  10
420 ÷ 60 = 7
  10
4,200 ÷ 600 = 7
Helpful Hint

6. Additional Example 1A: Dividing a Decimal by a Decimal
Find the quotient.
5.2 ÷ 1.3
Multiply the divisor and dividend by the same power of ten. 4
There is one decimal place in the divisor. Multiply by 101, or 10.
Think: 1.3 x 10 = x 10 = 52
13 52
–52
Divide.
5.2 ÷ 1.3 = 4

7. Additional Example 1B: Dividing a Decimal by a Decimal
61.3 ÷ 0.36
Make the divisor a whole number by multiplying the divisor and dividend by 102, or 100.
Think: 0.36 x 100 = x 100 = 6,130
36 6,

8. Additional Example 1B Continued7 .2 7 7
36 6,
Place the decimal point in the quotient. Divide.
-36
253
-252 10 -0
When a repeating pattern occurs, show three dots or draw a bar over the repeating part of the quotient.
100
-72
280
-252
280
61.3 ÷ 0.36 = __
-252 28

9. Multiply the divisor and dividend by the same power of ten. 1.1 6.6
Check It Out: Example 1A
Find the quotient.
6.6 ÷ 1.1
Multiply the divisor and dividend by the same power of ten. 6
There is one decimal place in the divisor. Multiply by 10 , or 10.
Think: 1.1 x 10 = x 10 = 66 1
11 66
-66
Divide.
6.6 ÷ 1.1 = 6

10. Check It Out: Example 1B
51.2 ÷ 0.24
Make the divisor a whole number by multiplying the divisor and dividend by 102, or 100.
Think: 0.24 x 100 = x 100 = 5,120

11. Check It Out: Example 1B Continued2 1 3 .3 3
24 5,120.00
Divide.
-48 32
-24 80
-72
When a repeating pattern occurs, show three dots or draw a bar over the repeating part of the quotient. 80
-72 80
-72 8
51.2 ÷ 0.24 = 213.3 __

12. Understand the Problem
Additional Example 2: Problem Solving Application
After driving miles, the York’s filled up with 10.5 gallons of gas. On average, how many miles did they drive per gallon of gas? 1
Understand the Problem
The answer will be the average number of miles per gallon.
List the important information:
They drove miles. They used 10.5 gallons of gas.

13. 2
Make a Plan
Solve a simpler problem by replacing the decimals in the problem with whole numbers.
If they drove 10 miles using 2 gallons of gas, they averaged 5 miles per gallon. You need to divide miles by gallons to solve the problem.
Solve 3
First estimate the answer. You can use compatible numbers.
216.3 ÷ ÷ 10 = 20

14. 3
Solve Continued
Multiply the divisor and dividend by 10. Think: 10.5 x 10 = x 10 = 2,163 2 .6
Place the decimal point in the quotient. Divide.
-210 63 -0
630
-630
The York family averaged 20.6 miles per gallon.

15. Look Back 4
The answer is reasonable since 20.6 is close to the estimate of 20.

16. Understand the Problem
Check It Out: Example 2
After driving miles, the Chang’s filled up with 10.5 gallons of gas. On average, how many miles did they drive per gallon of gas? 1
Understand the Problem
The answer will be the average number of miles per gallon.
List the important information:
They drove miles. They used 10.5 gallons of gas.

17. 2
Make a Plan
Solve a simpler problem by replacing the decimals in the problem with whole numbers.
If they drove 10 miles using 2 gallons of gas, they averaged 5 miles per gallon. You need to divide miles by gallons to solve the problem.
Solve 3
First estimate the answer. You can use compatible numbers.
191.1 ÷ ÷ 10 = 19

18. 3
Solve Continued
Multiply the divisor and dividend by 10. Think: 10.5 x 10 = x 10 = 1,911 1 8 .2
Place the decimal point in the quotient. Divide.
-105
861
-840
210
-210
The Chang family averaged 18.2 miles per gallon.

19. Look Back 4
The answer is reasonable since 18.2 is close to the estimate of 19.

20. Lesson Quizzes
Standard Lesson Quiz
Lesson Quiz for Student Response Systems

21. Lesson Quiz
Find each quotient.
1. 49 ÷ 0.7
÷ 2.1
÷ 6.1
÷ 5.2
5. John spent $13.44 renting 4 videos for the weekend. What was the cost per video? 70
10.3
6.3
3.25
$3.36

22. Lesson Quiz for Student Response Systems
1. Identify the quotient.
72  0.9
A. 70
B. 79
C. 80
D. 90

23. Lesson Quiz for Student Response Systems
2. Identify the quotient.
36.12  4.2
A. 8.6
B. 8.8
C. 9.5
D. 9.6

24. Lesson Quiz for Student Response Systems
3. Identify the quotient.
51.51  5.1
A. 10.1
B. 10
C. 5.1
D. 5

25. Lesson Quiz for Student Response Systems
4. Identify the quotient.
26.35  6.2
A. 4.25
B. 4.5
C. 4.75
D. 5

26. Lesson Quiz for Student Response Systems
5. Dee bought 5 cups of iced tea for $4.85. What was the cost per cup?
A. $0.66
B. $0.69
C. $0.95
D. $0.97