8/12/2019 Pre Algebra Lesson 6 5

1/25

6-5 Multiplying and Dividing

Decimals

Objective: Multiply and divide

decimals.

8/12/2019 Pre Algebra Lesson 6 5

2/25

5-Minute Check

1. Name the multiplicative inverse of 12/5.

8/12/2019 Pre Algebra Lesson 6 5

3/25

5-Minute Check

1. Name the multiplicative inverse of 12/5.5/7

8/12/2019 Pre Algebra Lesson 6 5

4/25

5-Minute Check

1. Name the multiplicative inverse of 12/5.

Estimate the solution to each equation. Then solve. Write

the solution in simplest form.2. x = -6 1

8/12/2019 Pre Algebra Lesson 6 5

5/25

5-Minute Check

1. Name the multiplicative inverse of 12/5.

Estimate the solution to each equation. Then solve. Write

the solution in simplest form.2. x = -6 1 -4

8/12/2019 Pre Algebra Lesson 6 5

6/25

5-Minute Check

1. Name the multiplicative inverse of 12/5.

Estimate the solution to each equation. Then solve. Write

the solution in simplest form.2. x = -6 1

3. n = 5/127/15

8/12/2019 Pre Algebra Lesson 6 5

7/25

5-Minute Check

1. Name the multiplicative inverse of 12/5.

Estimate the solution to each equation. Then solve. Write

the solution in simplest form.2. x = -6 1

3. n = 5/127/15 25/28

8/12/2019 Pre Algebra Lesson 6 5

8/25

5-Minute Check

1. Name the multiplicative inverse of 12/5.

Estimate the solution to each equation. Then solve. Write

the solution in simplest form.2. x = -6 1

3. n = 5/127/15

Evaluate each expression if m = 1/3and n = -2/9

4. m/n

8/12/2019 Pre Algebra Lesson 6 5

9/25

5-Minute Check

1. Name the multiplicative inverse of 12/5.

Estimate the solution to each equation. Then solve. Write

the solution in simplest form.2. x = -6 1

3. n = 5/127/15

Evaluate each expression if m = 1/3and n = -2/9

4. m/n -1

8/12/2019 Pre Algebra Lesson 6 5

10/25

5-Minute Check

1. Name the multiplicative inverse of 12/5.

Estimate the solution to each equation. Then solve. Write

the solution in simplest form.2. x = -6 1

3. n = 5/127/15

Evaluate each expression if m = 1/3and n = -2/9

4. m/n

5. n/m2

8/12/2019 Pre Algebra Lesson 6 5

11/25

5-Minute Check

1. Name the multiplicative inverse of 12/5.

Estimate the solution to each equation. Then solve. Write

the solution in simplest form.2. x = -6 1

3. n = 5/127/15

Evaluate each expression if m = 1/3and n = -2/9

4. m/n

5. n/m

2 -2

8/12/2019 Pre Algebra Lesson 6 5

12/25

6-5 Multiplying and Dividing

DecimalsWhen multiplying decimals, the number

of decimal places in the product is the

same as the sum of the decimal places in

the factors.

8/12/2019 Pre Algebra Lesson 6 5

13/25

6-5 Multiplying and Dividing

DecimalsExample 1

Solve y = (10.7)(0.13).

10.7 1 decimal place

8/12/2019 Pre Algebra Lesson 6 5

14/25

6-5 Multiplying and Dividing

DecimalsExample 1

Solve y = (10.7)(0.13).

10.7

x0.13

1 decimal place

2 decimal places

8/12/2019 Pre Algebra Lesson 6 5

15/25

6-5 Multiplying and Dividing

DecimalsExample 1

Solve y = (10.7)(0.13).

10.7

x0.13321

1 decimal place

2 decimal places

8/12/2019 Pre Algebra Lesson 6 5

16/25

6-5 Multiplying and Dividing

DecimalsExample 1

Solve y = (10.7)(0.13).

10.7

x0.13321

1070

1 decimal place

2 decimal places

8/12/2019 Pre Algebra Lesson 6 5

17/25

6-5 Multiplying and Dividing

DecimalsExample 1

Solve y = (10.7)(0.13).

10.7

x0.13321

1070

1.391

1 decimal place

2 decimal places

3 decimal places

8/12/2019 Pre Algebra Lesson 6 5

18/25

6-5 Multiplying and Dividing

DecimalsExample 1

Solve y = (10.7)(0.13).

10.7

x0.13321

1070

1.391

y = 1.391

1 decimal place

2 decimal places

3 decimal places

8/12/2019 Pre Algebra Lesson 6 5

19/25

6-5 Multiplying and Dividing

DecimalsTo divide decimals, multiply both the

divisor and the dividend by a power of

ten so that the divisor is a wholenumber. Then divide.

8/12/2019 Pre Algebra Lesson 6 5

20/25

6-5 Multiplying and Dividing

DecimalsExample 2

Solve y = 2.25 2.5.

8/12/2019 Pre Algebra Lesson 6 5

21/25

6-5 Multiplying and Dividing

DecimalsExample 2

Solve y = 2.25 2.5.

Estimate: 2 2 = 1

2.5)2.25

8/12/2019 Pre Algebra Lesson 6 5

22/25

6-5 Multiplying and Dividing

DecimalsExample 2

Solve y = 2.25 2.5.

Estimate: 2 2 = 1

2.5)2.25 Multiply by 10 to get a whole number inthe divisor.

8/12/2019 Pre Algebra Lesson 6 5

23/25

6-5 Multiplying and Dividing

DecimalsExample 2

Solve y = 2.25 2.5.

Estimate: 2 2 = 1

2.5)2.25

0.9

25)22.5225

Multiply by 10 to get a whole number inthe divisor.

Divide as with whole numbers.

8/12/2019 Pre Algebra Lesson 6 5

24/25

6-5 Multiplying and Dividing

DecimalsExample 2

Solve y = 2.25 2.5.

Estimate: 2 2 = 1

2.5)2.25

0.9

25)22.5225

x = 0.9

Multiply by 10 to get a whole number inthe divisor.

Divide as with whole numbers.

Compare to the estimate.

8/12/2019 Pre Algebra Lesson 6 5

25/25

6-5 Multiplying and Dividing

DecimalsAssignment: 1848 Even, 5062 All.

Page: 298+