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

2. Warm Up
Multiply.
1. 87  320
27,840
 800
754,400
3. 3,806  10
38,060
4. 1,207  100
120,700
5. 72  196
14,112
 523
62,760

3. Problem of the Day
Carmen and Rita sold homemade oatmeal cookies. After 8 days, they had sales totaling $70. Each day, their sales were $0.50 higher than the previous day. What were their sales on the first day?
$7.00

4. Sunshine State Standards
MA.6.A.1.2 Multiply…decimals efficiently.
MA.6.A.1.3 Solve real-world problems involving multiplication…of…decimals.
Also MA.6.A.1.1

5. Additional Example 1: Science Application
Something that weighs 1 lb on Earth weighs lb on the Moon. How much would a 4 lb dumbbell weigh on the Moon?
Multiply 4 by 0.17, since 1 pound on Earth is 0.17 pound on the Moon.
4  0.17 17
Multiply as you would with whole numbers.
 4 68

6. Additional Example 1 Continued
Something that weighs 1 lb on Earth weighs lb on the Moon. How much would a 4 lb dumbbell weigh on the Moon?
Place the decimal point by adding the number of decimal places in the numbers multiplied.
0.17
2 decimal places
 4
+ 0 decimal places
0.68
2 decimal places
A 4 lb dumbbell on Earth weighs 0.68 lb on the Moon.

7. Check It Out: Example 1
Something that weighs 1 lb on Earth weighs lb on the Moon. How much would a 7 lb dumbbell weigh on the Moon?
7 × 0.17 = 1.19 lb

8. You can use a decimal grid to model multiplication of decimals.
Helpful Hint

9. Additional Example 2A: Multiplying a Decimal by a Decimal
Find the product.
0.3  0.4
Multiply. Then place the decimal point.
1 decimal place
0.3 
+ 1 decimal place
0.4
2 decimal places
0.12

10. Additional Example 2B: Multiplying a Decimal by a Decimal
0.07  0.8
Estimate the product. 0.8 is close to 1.
0.07  1 = 0.07
Multiply. Then place the decimal point.
2 decimal places
0.07
 0.8
+ 1 decimal place
3 decimal places; use a placeholder zero
0.056
0.056 is close to the estimate of The answer is reasonable.

11. Additional Example 2C: Multiplying a Decimal by a Decimal
1.34  2.5
Estimate the product. Round each factor to the nearest whole number.
1  3 = 3
Multiply. Then place the decimal point.
1.34 
2.5
2 decimal places
670
+ 1 decimal place
2680
3 decimal places
3.350
3.350 is close to the estimate of 3. The answer is reasonable.

12.  Check It Out: Example 2 Find the product. 3.80 × 3.3 3.80 3.3 1140
11400
= 12.54

13. Additional Example 3A: Evaluating Decimal Expressions
Evaluate 5x for the value of x.
x = 3.062
Substitute for x.
5x = 5(3.062)
3 decimal places
3.062  5
+ 0 decimal places
15.310
3 decimal places
These notations all mean multiply 3 times x.
3 • x 3x 3(x)
Remember!

14. Additional Example 3B: Evaluating Decimal Expressions
Evaluate 5x for the value of x.
x = 4.79
Substitute 4.79 for x.
5x = 5(4.79)
2 decimal places
4.79  5
+ 0 decimal places
23.95
2 decimal places

15. Check It Out: Example 3
Evaluate 5x for the value of x.
x = 6.22
5(6.22) = = 31.1

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

17. Lesson Quiz
Find each product.
 0.07
 0.07
Evaluate 8x for each value of x.
0.056
3. x = x = 0.804
21.64
6.432
5. “Pick your own” peaches sell for $0.95 per pound. You picked 92 pounds of peaches. How much were you charged?
$87.40

18. Lesson Quiz for Student Response Systems
1. Identify the product.
0.29  0.01
A. 0.29 B C D

19. Lesson Quiz for Student Response Systems
2. Identify the product.
0.052  0.03 A B C D

20. Lesson Quiz for Student Response Systems
3. Evaluate 4x for x =
A. 21
B. 21.2 C
D. 21.3

21. Lesson Quiz for Student Response Systems
4. Evaluate 9x for x =
A. 10.8
B. 1.08 C D

22. Lesson Quiz for Student Response Systems
5. Strawberry lemonade costs $0.89 per packet. Karen bought 58 packets of strawberry lemonade for a picnic. How much did she pay for it?
A. $51.62
B. $51.86
C. $52.54
D. $52.93