Name 5.35.3Use Models Use Models

to Multiply to Multiply Decimals and Decimals and

Whole NumbersWhole NumbersLearning Target:Learning Target: Use models to multiply decimals Use models to multiply decimals and whole numbers.and whole numbers.Success Criteria:Success Criteria: • I can use a model to represent a decimal.• I can use a model to represent a decimal.• I can explain the relationship between addition and • I can explain the relationship between addition and

multiplication.multiplication.• I can use a model to find the product of a decimal and• I can use a model to find the product of a decimal and

a whole number.a whole number.

Explore and Grow

Chapter 5 ⎜ Lesson 3 187

Complete the table.

Structure How does the relationship between addition and multiplication help you find each product?

Expression 0.2 × 4 0.15 × 3

Model

Repeated Addition

Value

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Think and Grow: Understand Multiplicative ComparisonThink and Grow: Use Models to Multiply Decimals and Whole Numbers

188

Find the product.

1. 1. 0.19 × 3 = 2. 2. 0.37 × 5 =

Show and GrowShow and GrowSSSShhhhhhhhoowwwwwww aannnddddddd GGGGrrrrrrroowwwwwwwSSSSSSSShhhhhhhhoooooooowwwwwwww aaaaaaaannnnnnnndddddddd GGGGGGGGrrrrrrrroooooooowwwwwwwwShow and GrowShow and Grow

Use a model. Shade 3 groups of 0.23.

Use a model. Shade 4 groups of 0.48.

Example Find 0.23 × 3.

Example Find 0.48 × 4.

0.23 + 0.23 + 0.23 =

0.48 + 0.48 + 0.48 + 0.48 =

So, 0.23 × 3 = .

So, 0.48 × 4 = .

.

Remember, each part of the model represents

one hundredth.

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189Chapter 5 ⎜ Lesson 3

Name

Find the product.

7. 7. A hummingbird’s heart beats once every 0.05 second. How long does it take for its heart to beat 7 times?

3. 3. 0.09 × 5 =

5. 5. 7 × 0.14 =

4. 4. 8 × 0.2 =

6 . 6 . 0.96 × 2 =

Apply and Grow: Practice

8. 8. Precision When multiplying a decimal less than one by a whole number, how does the product compare to the whole number? Is this true when multiplying two whole numbers?

9. 9. DIG DEEPER Write two multiplication equations involving a decimal and a whole number whose product is shown.

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Think and Grow: Modeling Real Life

190

Show and GrowShow and GrowSSSShhhhhhhhoowwwwwwww aannnnndddddddd GGGGGGrrrrrrroowwwwwwSSSSSSSShhhhhhhhoooooooowwwwwwww aaaaaaaannnnnnnndddddddd GGGGGGGGrrrrrrrroooooooowwwwwwwwShow and GrowShow and Grow10. 10. You have 1 meter of ribbon.

Do you have enough ribbon to border the outside of the square picture frame?

11. 11. Organic shaved coconut originally costs $0.34 per ounce. A baker buys 8 ounces on sale for $0.27 per ounce. How much money does the baker save?

Example You build the card tower shown. Each row is 0.08 meter tall. Your friend’s card tower is 0.3 meter tall. Whose tower is taller?

Because your card tower has 4 rows, multiply 4 by 0.08 to find the height of your tower.

Use a model. Shade 4 groups of 0.08.

0.08 + 0.08 + 0.08 + 0.08 =

Compare the height of your tower to the height of your friend’s tower.

So, tower is taller.

0.33 m

12. 12. DIG DEEPER You have 4 pennies, 3 nickels, and 2 quarters. Find the total weight and the total value of your coins.

Coin

Weight (g) 2.5 5 2.268 5.67

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Name Homework & Practice 5.35.3

Learning Target:Learning Target: Use models to multiply Use models to multiply decimals and whole numbers.decimals and whole numbers.

191Chapter 5 ⎜ Lesson 3

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Find the product.

1. 1. 0.4 × 2 =

3. 3. 0.54 × 3 =

2. 2. 6 × 0.31 =

4. 4. 0.25 × 7 =

Example Find 0.16 × 5.

Use a model. Shade 5 groups of 0.16.

0.16 + 0.16 + 0.16 + 0.16 + 0.16 = 0.80

So, 0.16 × 5 = .0.80

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Review & RefreshEvaluate the expression.

13. 13. (11 + 7) ÷ (3 + 5 + 1) 14. 14. 35 ÷ [(153 − 139) ÷ 2]12. 12. (12 ÷ 4) × 30 − 15

192

7. 7. A city mayor plans to build two new parks. Each park will cover 1.45 acres. How many acres will the new parks cover altogether? Explain.

8. 8. Structure Write an equation represented by the model.

9. 9. DIG DEEPER Find the product of 0.03 and 4. How does the product change when you replace 4 with 0.4? Explain.

10. 10. Modeling Real Life In 1 year, you spend $1.50 on electricity to charge your tablet. In 1 month, you spend $0.02 on electricity to charge your smartphone. Which device costs more to charge in 1 year?

Find the product.

5. 5. 0.22 × 4 = 6. 6. 5 × 0.4 =

11. 11. DIG DEEPER You have a 2-pound carton of blueberries. You eat 0.2 of the carton on Monday and 0.35 of the carton on Tuesday. How many pounds of blueberries are left?

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