Transcript Slide 1

Name __________________________
Learning Objective
Today, we will multiply decimal numbers.
CFU
What are we going to do today?
Activate (or provide) Prior Knowledge
Multiplication is repeated addition of equal groups.
• A factor is a number used in a multiplication problem.
• The product is the answer to a multiplication problem.
3 factors
 4
12 product
Solve the multiplication problems on your whiteboards.
1.
2
2 1 5

4
8 6 0
2.
1
1 2 6

3
3 7 8
CFU
Students, you already know how to multiply with whole numbers. Today, we will use these skills to multiply decimal numbers.
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5th Grade Number Sense 2.1 (7Q)
Add, subtract, multiply, and divide with decimals; add with negative integers; subtract
positive integers from negative integers; and verify the reasonableness of the results.
Lesson to be used by EDI-trained teachers only.
Concept Development
To multiply is to do repeated addition of equal groups.
A decimal number represents a whole number and a part of a whole number separated by a decimal point.
To multiply decimal numbers:
• Decimal numbers do not need to be lined up by place value.
• The number of decimal places in the product is equal to the total number of decimal places in the numbers being
multiplied.
Multiplying Decimal Numbers
Jimmy receives $2.15
every day for
allowance. How much
will he have if he
saves his money for
five days?
2.15
2.15
2.15
2.15
+ 2.15
10.75
.
2
2 1 5

5
1 0 7 5
.
Jimmy will have $10.75 if he saves
his allowance for five days.
CFU
On your whiteboard, write a decimal number. How do you know it is a decimal number?
Look at the multiplication problem on the right. How many decimal places would there be on the right in the product?
A 1
B 2
C 3
D 4
Between which two digits would the decimal point be placed in the product?
In your own words, what is the main difference between multiplying whole numbers and decimal numbers?
The main difference is _____________.
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.
.
.
4

1 3 2
2
3
6
8
1
8
Flashcards
Decimal Point Placement
5th Grade Number Sense 2.1 (7Q)
Add, subtract, multiply, and divide with decimals; add with negative integers; subtract
positive integers from negative integers; and verify the reasonableness of the results.
Lesson to be used by EDI-trained teachers only.
Skill Development/Guided Practice
To multiply decimal numbers:
• The number of decimal places in the product is equal to the total number of
decimal places in the numbers being multiplied.
Multiply Decimal Numbers
.1

1 0 .7
2
Multiply decimal numbers.
Step #1: Multiply the bottom factor with each digit of the top factor.
(regroup if needed)
a. Add regrouped numbers, if any.
Step #2: Count the total number of decimal places in the two factors.
a. Place a decimal in the product that many places to the left.
1.
2
.
.
2.
1
1 4

7
9 8
4.
1
.
.

.
.
5
2 decimal places
5
5
0 decimal places
3.
3
2 decimal places
.
.
1
1 2
1 7 3
8
9 6

5
8 6 5
5.
6.
3
4
1 2 6
6 2
8 7

6
7 5 6
 0 4
2 4 8
 0 6
5 2 2
.
.
.
.
CFU
(#2) How did I/you count the total number of decimal places in the two factors?
(#2a) How did I/you place a decimal in the product that many places to the left?
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©2012 All rights reserved.
Comments? [email protected]
5th Grade Number Sense 2.1 (7Q)
Add, subtract, multiply, and divide with decimals; add with negative integers; subtract
positive integers from negative integers; and verify the reasonableness of the results.
Lesson to be used by EDI-trained teachers only.
Skill Development/Guided Practice (continued)
To multiply decimal numbers:
• The number of decimal places in the product is equal to the total number of
decimal places in the numbers being multiplied.
Multiply Decimal Numbers
.1

1 0 .7
2
Multiply decimal numbers.
Step #1: Multiply the bottom factor with each digit of the top factor.
(regroup if needed)
a. Add regrouped numbers, if any.
Step #2: Count the total number of decimal places in the two factors.
a. Place a decimal in the product that many places to the left.
7.
2
8.
.
.

3
1 7 4 3 3
11.
.
.
.
6 2
 0 4
2 4 8
.
.
.
1
1
4 6 7 1
 0 0 2
0 9 3 4 2
2 decimal places
5
5
0 decimal places
2 decimal places
9.
4
7 3 5 2

2
14 7 0 4
5 8 1 1
10.
.
.
1
5
.
.
8 7
 0 6
5 2 2
.
12.
.
.
.
1
2
1
2 4 6 3
 0 0 4
0 9 8 5 2
CFU
(#2) How did I/you count the total number of decimal places in the two factors?
(#2a) How did I/you place a decimal in the product that many places to the left?
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©2012 All rights reserved.
Comments? [email protected]
5th Grade Number Sense 2.1 (7Q)
Add, subtract, multiply, and divide with decimals; add with negative integers; subtract
positive integers from negative integers; and verify the reasonableness of the results.
Lesson to be used by EDI-trained teachers only.
Relevance
To multiply decimal numbers:
• The number of decimal places in the product is equal to the total number of decimal places in the numbers being
multiplied.
1. Multiplying decimal numbers will help you determine the cost of multiple items.
$0.51 for 1 pencil sharpener.
$0.51  3 =$1.53
$1.53 for 3 pencil sharpeners.
2. Multiplying decimal numbers will help you convert measurement.
One inch equals 2.54 centimeters. 2.54
A box is 14 inches long, how
x 14
35.56
many centimeters long is it?
The box is 35.56
centimeters long.
3. Multiplying decimal numbers will help you do well on tests.
CFU
Does anyone else have another reason why it is relevant to multiply decimal numbers? (pair-share) Why is it relevant to multiply decimal
numbers? You may give me one of my reasons or one of your own. Which reason is most relevant to you? Why?
5th Grade Number Sense 2.1 (7Q)
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Add, subtract, multiply, and divide with decimals; add with negative integers; subtract
positive integers from negative integers; and verify the reasonableness of the results.
Lesson to be used by EDI-trained teachers only.
To multiply decimal numbers:
• The number of decimal places in the product is equal to the total number of decimal places
in the numbers being multiplied.
Multiply Decimal Numbers
Skill Closure
Multiply decimal numbers.
.1

1 0 .7
2
Step #1: Multiply the bottom factor with each digit of the top factor.
(regroup if needed)
a. Add regrouped numbers, if any.
Step #2: Count the total number of decimal places in the two factors.
a. Place a decimal in the product that many places to the left.
1.
2
.
.
2.
1
2 decimal places
5
5
0 decimal places
2 decimal places
..
2 6
3 2

4
1 0 4
 0 7
2 2 4
.
5
Concept Closure
Look at the multiplication problem below. Where would you place the decimal points in the factors if the
product was 1.6892? Explain your answer. Hint: There are multiple answers.
1 0 3
1 6 4
__________________________________________________________________________________________________________
__________________________________________________________________________________________________________
__________________________________________________________________________________________________________
What did you learn today about multiplying decimal numbers?
Day 1 ________________________________________________________________________________________________
Day 2 ________________________________________________________________________________________________
DataWORKS Educational Research
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©2012 All rights reserved.
Comments? [email protected]
5th Grade Number Sense 2.1 (7Q)
Add, subtract, multiply, and divide with decimals; add with negative integers; subtract
positive integers from negative integers; and verify the reasonableness of the results.
Lesson to be used by EDI-trained teachers only.
Name _____________________________
Independent Practice
To multiply decimal numbers:
• The number of decimal places in the product is equal to the total number of
decimal places in the numbers being multiplied.
Multiply Decimal Numbers
.1

1 0 .7
2
Multiply decimal numbers.
Step #1: Multiply the bottom factor with each digit of the top factor.
(regroup if needed)
a. Add regrouped numbers, if any.
Step #2: Count the total number of decimal places in the two factors.
a. Place a decimal in the product that many places to the left.
1.
4
2.
.
.
2
3 6
.
.
3
2
7 2 5 4

6
4 3 5 2 4
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0 decimal places
2 decimal places
3.
4
4
8
18 8 0
 0 5
1 4 5
5.
1
5
5
2 9
x
4.
2 decimal places
3 5
2

8
2 8 8
.
.
5
.
.
6.
2
.
.
2
.
2
1
6 3
6 5 4 2
 0 8
5 0 4

0 5
3 2 7 1 0
.
.
.
5th Grade Number Sense 2.1 (7Q)
Add, subtract, multiply, and divide with decimals; add with negative integers; subtract
positive integers from negative integers; and verify the reasonableness of the results.
Lesson to be used by EDI-trained teachers only.
Name _____________________________
Periodic Review 1
To multiply decimal numbers:
• The number of decimal places in the product is equal to the total number of
decimal places in the numbers being multiplied.
Multiply Decimal Numbers
.1

1 0 .7
2
Multiply decimal numbers.
Step #1: Multiply the bottom factor with each digit of the top factor.
(regroup if needed)
a. Add regrouped numbers, if any.
Step #2: Count the total number of decimal places in the two factors.
a. Place a decimal in the product that many places to the left.
1.
2.
1

.
.
5
5
0 decimal places
2 decimal places
3.
1
.
.
4
2
4 3 9
8 7
2
7 2

3
1 3 1 7
 0 6
5 2 2
5.
.
.
3
4 3 3
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..
6.
1
5 8 1 1

17
2 decimal places
3 6
4.
2
5
.
.
3 2
 0 8
2 5 6
.
5
.
1
4 7 2 1

0 8
3 7 7 6 8
.
.
5th Grade Number Sense 2.1 (7Q)
Add, subtract, multiply, and divide with decimals; add with negative integers; subtract
positive integers from negative integers; and verify the reasonableness of the results.
Lesson to be used by EDI-trained teachers only.
Name _____________________________
Periodic Review 2
To multiply decimal numbers:
• The number of decimal places in the product is equal to the total number of
decimal places in the numbers being multiplied.
Multiply Decimal Numbers
.1

1 0 .7
2
Multiply decimal numbers.
Step #1: Multiply the bottom factor with each digit of the top factor.
(regroup if needed)
a. Add regrouped numbers, if any.
Step #2: Count the total number of decimal places in the two factors.
a. Place a decimal in the product that many places to the left.
1.
2.
3
.
.

5
1 8 0
4.
.
.
1
2 decimal places
.
.
1
7 2

5
23 6 0
 0 7
5 0 4
..
6.
1
.
.
4 9 2 4
3 4

6
29 5 4 4
 0 3
1 0 2
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0 decimal places
4 7 2
2
DataWORKS Educational Research
5
5
1
5.
5
2 decimal places
3.
3
3 6
5
.
5
.
6
3
3 5 7 4

0 9
3 2 1 6 6
.
.
5th Grade Number Sense 2.1 (7Q)
Add, subtract, multiply, and divide with decimals; add with negative integers; subtract
positive integers from negative integers; and verify the reasonableness of the results.
Lesson to be used by EDI-trained teachers only.
Name _____________________________
Periodic Review 3
To multiply decimal numbers:
• The number of decimal places in the product is equal to the total number of
decimal places in the numbers being multiplied.
Multiply Decimal Numbers
.1

1 0 .7
2
Multiply decimal numbers.
Step #1: Multiply the bottom factor with each digit of the top factor.
(regroup if needed)
a. Add regrouped numbers, if any.
Step #2: Count the total number of decimal places in the two factors.
a. Place a decimal in the product that many places to the left.
1.
2.
.
.

3
1 5 9
4.
.
.
2
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0 decimal places
2 decimal places
.
.
1
2 5 2
5 2

7
1 7 6 4
 0 7
3 6 4
..
6.
1
6 6 4 3

6
3 9 8 5 8
5
5
1
5.
3
2 decimal places
3.
3
5 3
5
2
.
.
.
2
4
4 3
4 1 3 7
 0 7
3 0 1

0 6
2 4 8 2 2
.
.
.
5th Grade Number Sense 2.1 (7Q)
Add, subtract, multiply, and divide with decimals; add with negative integers; subtract
positive integers from negative integers; and verify the reasonableness of the results.
Lesson to be used by EDI-trained teachers only.
Flashcards (Decimal Point Placement)
To multiply decimal numbers:
• The number of decimal places in the product is equal to the total number of decimal places in the numbers being
multiplied.
Teacher
with CFU
If the product is 231.15, where would the
decimal points be in the factors?
.
.
3 4 5
 6 7
How did I know where to put the decimal point for each factor?
DataWORKS Educational Research
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©2012 All rights reserved.
Comments? [email protected]
5th Grade Number Sense 2.1 (7Q)
Add, subtract, multiply, and divide with decimals; add with negative integers; subtract
positive integers from negative integers; and verify the reasonableness of the results.
Lesson to be used by EDI-trained teachers only.
Flashcards (Decimal Point Placement)
To multiply decimal numbers:
• The number of decimal places in the product is equal to the total number of decimal places in the numbers being
multiplied.
Student
with CFU
If the product is 10.528, where would the
decimal points be in the factors?
.
2 2 4
 4 7
.
How did you know where to put the decimal point for each factor?
DataWORKS Educational Research
(800) 495-1550 • www.dataworks-ed.com
©2012 All rights reserved.
Comments? [email protected]
5th Grade Number Sense 2.1 (7Q)
Add, subtract, multiply, and divide with decimals; add with negative integers; subtract
positive integers from negative integers; and verify the reasonableness of the results.
Lesson to be used by EDI-trained teachers only.
Flashcards (Decimal Point Placement)
To multiply decimal numbers:
• The number of decimal places in the product is equal to the total number of decimal places in the numbers being
multiplied.
Student
If the product is 0.4504, where would the
decimal points be in the factors?
.5
6 3

8
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©2012 All rights reserved.
Comments? [email protected]
.
5th Grade Number Sense 2.1 (7Q)
Add, subtract, multiply, and divide with decimals; add with negative integers; subtract
positive integers from negative integers; and verify the reasonableness of the results.
Lesson to be used by EDI-trained teachers only.
Flashcards (Decimal Point Placement)
To multiply decimal numbers:
• The number of decimal places in the product is equal to the total number of decimal places in the numbers being
multiplied.
Student
If the product is .52241, where would the
decimal points be in the factors?
.1
1 9
4 3 9
DataWORKS Educational Research
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©2012 All rights reserved.
Comments? [email protected]
.
5th Grade Number Sense 2.1 (7Q)
Add, subtract, multiply, and divide with decimals; add with negative integers; subtract
positive integers from negative integers; and verify the reasonableness of the results.
Lesson to be used by EDI-trained teachers only.
Flashcards (Decimal Point Placement)
To multiply decimal numbers:
• The number of decimal places in the product is equal to the total number of decimal places in the numbers being
multiplied.
Student
If the product is 41.28, where would the
decimal points be in the factors?
.
.
9 6
 4 3
DataWORKS Educational Research
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©2012 All rights reserved.
Comments? [email protected]
5th Grade Number Sense 2.1 (7Q)
Add, subtract, multiply, and divide with decimals; add with negative integers; subtract
positive integers from negative integers; and verify the reasonableness of the results.
Lesson to be used by EDI-trained teachers only.
Flashcards (Decimal Point Placement)
To multiply decimal numbers:
• The number of decimal places in the product is equal to the total number of decimal places in the numbers being
multiplied.
Student
with CFU
If the product is 1.6, where would the
decimal points be in the factors?
8
 2
.
How did you know where to put the decimal point for each factor?
Back to Skill
Development
DataWORKS Educational Research
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©2012 All rights reserved.
Comments? [email protected]
5th Grade Number Sense 2.1 (7Q)
Add, subtract, multiply, and divide with decimals; add with negative integers; subtract
positive integers from negative integers; and verify the reasonableness of the results.
Lesson to be used by EDI-trained teachers only.