Transcript Correct Homework

01/06/10
Divide Decimals
#5
LT: I will divide decimals.
Warm Up:
1) 5×7
4) 9×7
7) 7×2
10) 7×6
2) 1×7
5) 7×10
8) 7×3
11) 7×100
3) 4×7
6) 7×8
9) 7×7
12) 7×11
Today’s Plan:
-Multiplication Practice
-Correct Homework
-Divide Decimals
Learning Target:
-I will divide decimals.
01/06/10
Divide Decimals
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.
#5
01/06/10
Divide Decimals
LT: I will divide decimals.
Correct Homework
Today’s Plan:
-Multiplication Practice
-Correct Homework
-Divide Decimals
Learning Target:
-I will divide decimals.
#5
Dividing Decimals and
4-5 Integers by Decimals
Additional Example 1A: Dividing Decimals by
Decimals
Divide.
A. 8.28 ÷ 4.6
8.28 ÷ 4.6 = 82.8 ÷ 46
1.8
46) 82.8
– 46
36 8
–36 8
Multiply both numbers by 10.
Divide as with whole numbers.
0
Helpful Hint
Multiply both numbers by the least power of ten that will
make the divisor an integer.
Course 2
Dividing Decimals and
4-5 Integers by Decimals
Additional Example 1B: Dividing Decimals by
Decimals
Divide.
B. 18.48 ÷ (–1.75)
18.48 ÷ (–1.75) =
1848 ÷ 175
1 0.5 6
175 ) 1848 . 00
–175
98 0
–87 5
10 50
–10 50
0
18.48 ÷ (–1.75) = –10.56
Course 2
Multiply both numbers by
100.
Use zeros as placeholders
Divide as with whole
numbers.
The signs are different.
Dividing Decimals and
4-5 Insert
Lesson
Title Here
Integers
by Decimals
Try This: Example 1A
Divide.
A. 6.45 ÷ 0.5
6.45 ÷ 0.5 = 64.5 ÷ 5
12 . 9
5 ) 64.5
–5
14
–10
45
–4 5
0
Course 2
Multiply both numbers by10.
Divide as with whole numbers.
Dividing Decimals and
4-5 Integers by Decimals
Try This: Example 1B
Divide.
B. 16.48 ÷ (–2.06)
16.48 ÷ (–2.06) = 1648 ÷ (206)
8
206)1,648
–1 648
0
16.48 ÷ (–2.06) = –8
Course 2
Multiply both
numbers by 100.
Divide as with whole numbers.
The signs are different.
Dividing Decimals and
4-5 Integers by Decimals
Additional Example 2A: Dividing Integers by
Decimals
Divide. Estimate to check whether the answer
is reasonable.
A. 4 ÷ 1.25
4.00 ÷ 1.25 = 400 ÷ 125
3. 2
125 ) 400 .0
–375
25 0
–25 0
0
Estimate
4÷1=4
Course 2
Multiply both numbers by 100.
Use zero as a placeholder.
Divide as with whole numbers.
The answer is reasonable.
Dividing Decimals and
4-5 Integers by Decimals
Additional Example 2B: Dividing Integers by
Decimals
Divide. Estimate to check whether the answer
is Reasonable.
B. –24 ÷ (–2.5)
–24.0 ÷ (–2.5) = –240 ÷ (–25)
9. 6
25 ) 240 .0
– 225
15 0
– 15 0
0
Estimate
–24 ÷ (–3) = 8
Course 2
Multiply both numbers by 10.
Divide as with whole numbers.
The answer is reasonable.
Dividing Decimals and
4-5 Integers by Decimals
Try This: Example 2A
Divide. Estimate to check whether the answer
is reasonable.
A. 6 ÷ 1.25
6.00 ÷ 1.25 = 600 ÷ 125
4. 8
125 ) 600 .0
–500
100 0
–100 0
0
Estimate
6÷1=6
Course 2
Multiply both numbers by 100.
Use zero as a placeholder.
Divide as with whole numbers.
The answer is reasonable.
Dividing Decimals and
4-5 Integers by Decimals
Try This: Example 2B
Divide. Estimate to check whether the answer
is Reasonable.
B. –22 ÷ (–2.5)
–22.0 ÷ (–2.5) = –220 ÷ (–25)
8. 8
25 ) 220 .0
–200
20 0
–20 0
0
Estimate
–22 ÷ (–3) = 7
Course 2
Multiply both numbers by 10.
Divide as with whole numbers.
The answer is reasonable.
4-4 Dividing Decimals by Integers
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 ) 23.52
Place the decimal point for the answer
21 6
directly above the decimal under the
division symbol.
1 92
–1 92
0
One bottle of juice costs $0.98
$0.98 + $0.75 = $1.73
and a bag of peanuts costs $0.75
Kevin spent a total of $1.73
Course 2
4-4 Insert
Lesson
Titleby
Here
Dividing
Decimals
Integers
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.
0.15
12 ) 1.80
12
60
– 60
0
$1.79 + $0.15 =
Place the decimal point for the answer
directly above the decimal under the
division symbol.
$1.94
John spent a total of $1.94.
Course 2
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.
7.2
5 ) 36.0
36 ÷ 5 = 7.2
– 35
10
– 10
0
01/06/10
Divide Decimals
LT: I will divide decimals.
Page 212 #1-6
Today’s Plan:
-Multiplication Practice
-Correct Homework
-Divide Decimals
Learning Target:
-I will divide decimals.
#5