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01/06/10 Divide Decimals #5
Today’s Plan:-Multiplication Practice-Correct Homework-Divide Decimals
Learning Target: -I will divide decimals.
Warm Up:
1) 5×7
2) 1×7
3) 4×7
4) 9×7
5) 7×10
6) 7×8
7) 7×2
8) 7×3
9) 7×7
10) 7×6
11) 7×100
12) 7×11
LT: I will divide decimals.
LT: I will divide decimals.
Timed Test tomorrow 1-7
01/06/10 Divide Decimals #5
Today’s Plan:-Multiplication Practice-Correct Homework-Divide Decimals
Learning Target: -I will divide decimals.
LT: I will divide decimals.
Correct Homework
01/06/10 Divide Decimals #5
Today’s Plan:-Multiplication Practice-Correct Homework-Divide Decimals
Learning Target: -I will divide decimals.
Divide.
Additional Example 1A: Dividing Decimals by Decimals
8.28 ÷ 4.6
) 82.8461.
46–36 8
–36 8
Multiply both numbers by 10.
Divide as with whole numbers.
0
Multiply both numbers by the least power of ten that will make the divisor an integer.
Helpful Hint
A. 8.28 ÷ 4.6
8
= 82.8 ÷ 46
Course 2
4-5 Dividing Decimals and Integers by Decimals
Divide.
Additional Example 1B: Dividing Decimals by Decimals
B. 18.48 ÷ (–1.75)
18.48 ÷ (–1.75) = 1848 ÷ 175 Multiply both numbers by 100.
)175 1848 . 00 Use zeros as placeholdersDivide as with whole numbers.
1
–17598 0
0.5
–87 510 50
–10 50
0
18.48 ÷ (–1.75) = –10.56
6
The signs are different.
Course 2
4-5 Dividing Decimals and Integers by Decimals
Try This: Example 1A
Divide.
Insert Lesson Title Here
6.45 ÷ 0.5
) 64.5 51
5–14
–10
A. 6.45 ÷ 0.5
2
4 5
.9
–4 50
Multiply both numbers by10.
Divide as with whole numbers.
= 64.5 ÷ 5
Course 2
4-5 Dividing Decimals and Integers by Decimals
Divide.
B. 16.48 ÷ (–2.06)
16.48 ÷ (–2.06) = 1648 ÷ (206)
)1,6482068
–1 648
16.48 ÷ (–2.06) = –8
Multiply both numbers by 100.
Divide as with whole numbers.0
Try This: Example 1B
The signs are different.
Course 2
4-5 Dividing Decimals and Integers by Decimals
Divide. Estimate to check whether the answer is reasonable.
Additional Example 2A: Dividing Integers by Decimals
A. 4 ÷ 1.25
4.00 ÷ 1.25 = 400 ÷ 125 Multiply both numbers by 100.
)125 400 .0 Use zero as a placeholder.3
–37525 0
–25 0
0
Divide as with whole numbers.
Estimate4 ÷ 1 = 4 The answer is reasonable.
. 2
Course 2
4-5 Dividing Decimals and Integers by Decimals
Divide. Estimate to check whether the answer is Reasonable.
Additional Example 2B: Dividing Integers by Decimals
B. –24 ÷ (–2.5)
–24.0 ÷ (–2.5) = Multiply both numbers by 10.–240 ÷ (–25)
)25 2409
– 22515
.
.0
0
6
– 15 00
Estimate–24 ÷ (–3) = 8 The answer is reasonable.
Divide as with whole numbers.
Course 2
4-5 Dividing Decimals and Integers by Decimals
Divide. Estimate to check whether the answer is reasonable.
Try This: Example 2A
A. 6 ÷ 1.25
6.00 ÷ 1.25 = 600 ÷ 125 Multiply both numbers by 100.
)125 600 .0 Use zero as a placeholder.4
–500100 0
–100 00
Divide as with whole numbers.
Estimate6 ÷ 1 = 6 The answer is reasonable.
. 8
Course 2
4-5 Dividing Decimals and Integers by Decimals
Divide. Estimate to check whether the answer is Reasonable.
Try This: Example 2B
B. –22 ÷ (–2.5)
–22.0 ÷ (–2.5) = Multiply both numbers by 10.–220 ÷ (–25)
)25 2208
–20020
.
.0
0
8
–20 00
Estimate–22 ÷ (–3) = 7 The answer is reasonable.
Divide as with whole numbers.
Course 2
4-5 Dividing Decimals and Integers by Decimals
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?
Additional Example 2: Money Application
Course 2
4-4 Dividing Decimals by Integers
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)24 23.5221 61 92
–1 920
$0.98 + $0.75 = $1.73
Kevin spent a total of $1.73
.98Place the decimal point for the answerdirectly above the decimal under the division symbol.
One bottle of juice costs $0.98and a bag of peanuts costs $0.75
Try This: Example 2
Insert Lesson Title Here
Course 2
4-4 Dividing Decimals by Integers
0)12 1.801 2 60
– 600
$1.79 + $0.15 = $1.94
John spent a total of $1.94.
.15Place the decimal point for the answerdirectly above the decimal under the division symbol.
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.
One quart of milk costs$1.79 and one cookie costs $0.15.
Division Vocabulary
• The dividend is the number that is being divided. • The divisor is 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.
– 35)5 36.0
7.2
10 – 10
0
36 ÷ 5 = 7.2