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# 5 Minute Check - PowerPoint PPT Presentation

5 Minute Check. Complete in your notebook. 1 1. 3 x 12 3 2. 7 x 8 5 3. 6 x 15 2 4. 5 x 11. 5 Minute Check. Complete in your notebook. 1 1. 3 x 12. 5 Minute Check. Complete in your notebook. 1 1. 3 x 12 1 12 12

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1

1. 3x 12

3

2. 7 x 8

5

3. 6 x 15

2

4. 5x 11

1

1. 3x 12

1

1. 3 x 12

11212

3 x1 = 3 = 4

3

2. 7 x 8

3

2. 7 x 8

38243

7 x1 =7 = 3 7

5

3. 6 x 15

5

3. 6 x 15

51560

6 x1 =6 = 10

2

4. 5x 11

2

4. 5x 11

21122 2

5 x 1 = 5 =4 5

Lesson 4.3

Multiply Fractions

Objective: To understand how to multiply fractions.

At the end of this lesson you should be able to answer the following question.

If two positive fractions are less than one, why is the product also less than one?

To multiply fractions, multiply the numerators and multiply the denominators, then simplify if needed.

Example x =

32 63

4 x 5 = 20 = 10

x =

Multiply.

13

2 x 5=

Estimate?

Reminder – When estimating the product of two fractions, round each fraction to 0, ½ or 1 and then multiply.

Multiply.

13

2 x 5=

11 1

2 x 2 = 4

Actual Product?

Multiply Fractions

Multiply.

13

2 x 5=

Actual Product?

133

2 x 5= 10

Multiply.

13

2 x 5=

Actual Product?

133

2 x 5= 10

31

Is this a reasonable answer? 10 ≈ 4

Multiply.

25

3 x 6 =

Multiply Fractions

Multiply.

25

3 x 6 =

Estimate?

MuMultiply Fractions

Multiply.

25

3 x 6 =

11

2 x1= 2

Actual Product?

Multiply.

25

3 x 6 =

Actual Product?

25105

3 x 6 = 18 = 9

Multiply.

25

3 x 6 =

Actual Product?

25105

3 x 6 = 18 = 9

51

Is this a reasonable answer? 9 ≈ 2

If the numerators and denominators have a common factor you can simplify before multiplying.

If the numerators and denominators have a common factor you can simplify before multiplying.

Example

25

3 x 6 =

All numbers are prime factors (which means they have no factors other than one and itself), except for 6. What are the factors of 6?

If the numerators and denominators have a common factor you can simplify before multiplying.

Example

25

3 x 6 =

25

3 x2 x 3 =

Are there any factors that appear in the numerator and denominator?

If the numerators and denominators have a common factor you can simplify before multiplying.

Example

25

3 x 6 =

25

3 x2 x 3 =

2 the common to both

If the numerators and denominators have a common factor you can simplify before multiplying.

Example

25

3 x 6 =

25 5

3 x2 x 3 = 9

We can cancel the both 2’s.

Multiply.

4

9x 18=

Multiply.

4

9x 18=

41842 x 98

9 x 1 = 9x 1 = 1 = 8

Multiply.

3

5 x 10=

Multiply.

3

5 x 10=

3103 x 2 x 56

5x 1 = 5 x 1 = 1 = 6

Multiply Fractions

Frank had ½ of the lawn left to mow. On Saturday he mowed 2/3 of what was left. What fraction of the lawn did he mow on Saturday?

Frank had ½ of the lawn left to mow. On Saturday he mowed 2/3 of what was left. What fraction of the lawn did he mow on Saturday?

122 1

2x 3= 6 = 3

A paint store has 35 gallons of paint in storage, 2/5 of which are for outdoor use. The others are for indoor use. If each gallon costs \$22, what is the total cost of the indoor paint in storage?

A paint store has 35 gallons of paint in storage, 2/5 of which are for outdoor use. The others are for indoor use. If each gallon costs \$22, what is the total cost of the indoor paint in storage?

There is a couple of different ways to solve this problem.

If 2/5 is outdoor paint, what fraction is indoor paint?

A paint store has 35 gallons of paint in storage, 2/5 of which are for outdoor use. The others are for indoor use. If each gallon costs \$22, what is the total cost of the indoor paint in storage?

If 2/5 is outdoor paint, what fraction is indoor paint?3/5

What is 3/5 of 35 gallons?

A paint store has 35 gallons of paint in storage, 2/5 of which are for outdoor use. The others are for indoor use. If each gallon costs \$22, what is the total cost of the indoor paint in storage?

If 2/5 is outdoor paint, what fraction is indoor paint? 3/5

What is 3/5 of 35 gallons?

335105

5 x 1 = 5 =21

What is the cost of 21 gallons?

A paint store has 35 gallons of paint in storage, 2/5 of which are for outdoor use. The others are for indoor use. If each gallon costs \$22, what is the total cost of the indoor paint in storage?

What is the cost of 21 gallons?

21 x \$22 = \$462

If two positive fractions are less than one, why is the product also less than one?

Agenda Notes

Homework –

Homework Practice 4-3

Show all Work

Due Thursday, Oct 24

Mid Chapter 4 Quiz –Monday, Oct 28