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01/06/10 Divide Decimals#5

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01/06/10 Divide Decimals#5

LT: I will divide decimals.

- Warm Up:
- 5×7
- 1×7
- 4×7

- 9×7
- 7×10
- 7×8

- 7×2
- 7×3
- 7×7

- 7×6
- 7×100
- 7×11

Today’s Plan:

-Multiplication Practice

-Correct Homework

-Divide Decimals

Learning Target:

-I will divide decimals.

01/06/10 Divide Decimals#5

LT: I will divide decimals.

Timed Test tomorrow 1-7

Today’s Plan:

-Multiplication Practice

-Correct Homework

-Divide Decimals

Learning Target:

-I will divide decimals.

01/06/10 Divide Decimals#5

LT: I will divide decimals.

Correct Homework

Today’s Plan:

-Multiplication Practice

-Correct Homework

-Divide Decimals

Learning Target:

-I will divide decimals.

Dividing Decimals and Integers by Decimals

4-5

Helpful Hint

Multiply both numbers by the least power of ten that will make the divisor an integer.

Course 2

Additional Example 1A: Dividing Decimals by Decimals

Divide.

A. 8.28 ÷ 4.6

Multiply both numbers by 10.

8.28 ÷ 4.6

= 82.8 ÷ 46

1.

8

)

82.8

46

Divide as with whole numbers.

46

–

8

36

–36 8

0

Dividing Decimals and Integers by Decimals

4-5

Course 2

Additional Example 1B: Dividing Decimals by Decimals

Divide.

B. 18.48 ÷ (–1.75)

18.48 ÷ (–1.75) =

1848 ÷ 175

Multiply both numbers by

100.

1

0

.5

6

Use zeros as placeholders

)

.

00

175

1848

Divide as with whole

numbers.

–175

0

9

8

–87 5

10 50

–10 50

0

The signs are different.

18.48 ÷ (–1.75) = –10.56

Dividing Decimals and Integers by Decimals

4-5

Course 2

Insert Lesson Title Here

Try This: Example 1A

Divide.

A. 6.45 ÷ 0.5

6.45 ÷ 0.5

Multiply both numbers by10.

= 64.5 ÷ 5

1

2

9

.

)

5

Divide as with whole numbers.

64.5

5

–

14

–10

5

4

–4 5

0

Dividing Decimals and Integers by Decimals

4-5

Course 2

Try This: Example 1B

Divide.

B. 16.48 ÷ (–2.06)

Multiply both

numbers by 100.

1648 ÷ (206)

16.48 ÷ (–2.06) =

8

)

206

1,648

–1 648

Divide as with whole numbers.

0

16.48 ÷ (–2.06) = –8

The signs are different.

Dividing Decimals and Integers by Decimals

4-5

Course 2

Additional Example 2A: Dividing Integers by Decimals

Divide. Estimate to check whether the answer is reasonable.

A. 4 ÷ 1.25

Multiply both numbers by 100.

400 ÷ 125

4.00 ÷ 1.25 =

.

3

2

)

125

Use zero as a placeholder.

400

.0

Divide as with whole numbers.

–375

25 0

–25 0

0

Estimate

The answer is reasonable.

4 ÷ 1 = 4

Dividing Decimals and Integers by Decimals

4-5

Course 2

Additional Example 2B:Dividing Integers by Decimals

Divide. Estimate to check whether the answer is Reasonable.

B. –24 ÷ (–2.5)

Multiply both numbers by 10.

–24.0 ÷ (–2.5) =

–240 ÷ (–25)

9

6

.

)

0

240

.

Divide as with whole numbers.

25

– 225

0

15

– 15 0

0

Estimate

–24 ÷ (–3) = 8

The answer is reasonable.

Dividing Decimals and Integers by Decimals

4-5

Course 2

Try This: Example 2A

Divide. Estimate to check whether the answer is reasonable.

A. 6 ÷ 1.25

Multiply both numbers by 100.

600 ÷ 125

6.00 ÷ 1.25 =

.

4

8

)

125

Use zero as a placeholder.

600

.0

Divide as with whole numbers.

–500

100 0

–100 0

0

Estimate

The answer is reasonable.

6 ÷ 1 = 6

Dividing Decimals and Integers by Decimals

4-5

Course 2

Try This: Example 2B

Divide. Estimate to check whether the answer is Reasonable.

B. –22 ÷ (–2.5)

Multiply both numbers by 10.

–22.0 ÷ (–2.5) =

–220 ÷ (–25)

8

8

.

)

0

220

.

Divide as with whole numbers.

25

–200

0

20

–20 0

0

Estimate

–22 ÷ (–3) = 7

The answer is reasonable.

4-4

Dividing Decimals by Integers

Course 2

Additional Example 2: Money Application

You can buy juice by the bottle or case. Either way, it costs the same for each bottle. A case of 24 bottles of juice cost $23.52. Kevin bought a bag of peanuts for 75¢ and one bottle of juice. How much did Kevin spend in all?

First find the cost for one bottle of juice by dividing the cost of a case by the number of bottles in a case. Then add the cost of a bag of peanuts.

0

.

9

8

)

24

Place the decimal point for the answer

directly above the decimal under the

division symbol.

23.52

21 6

1 92

–1 92

0

One bottle of juice costs $0.98

and a bag of peanuts costs $0.75

$0.98 + $0.75 = $1.73

Kevin spent a total of $1.73

4-4

Dividing Decimals by Integers

Course 2

Insert Lesson Title Here

Try This: Example 2

Cookies at a store sell for $1.80 a dozen. The cost for each cookie is the same whether you buy them individually or by the dozen. John decided to buy 1 cookie and a quart of milk. The milk cost $1.79. How much did John have to pay?

First find the cost of one cookie by dividing the cost of a dozen by 12. Then add the price for the milk.

0

.

1

5

)

12

Place the decimal point for the answer

directly above the decimal under the

division symbol.

1.80

1 2

60

– 60

0

One quart of milk costs

$1.79 and one cookie

costs $0.15.

$1.79 + $0.15 = $1.94

John spent a total of $1.94.

- The dividendis the number that is being divided.
- The divisoris the number that the dividend will be divided by.
- The quotient is the number of times the divisor will go into the dividend. (The answer to the division problem.)
dividend÷divisor= quotient or quotient

divisor )dividend

- In this example 5 is the divisor, 36 is the dividend, 7.2 is the quotient.

7.2

36 ÷5= 7.2

)

5

36.0

– 35

10

– 10

0

01/06/10 Divide Decimals#5

LT: I will divide decimals.

Page 212 #1-6

Today’s Plan:

-Multiplication Practice

-Correct Homework

-Divide Decimals

Learning Target:

-I will divide decimals.