Multiplying Decimals

1
Multiplying Decimals Properties of
Multiplication

• Christine Berg
• Edited By V T Hamilton

2
Step 1

• Multiply as if the factors were whole numbers
  

3
Step 1

• 8.5
• X2.5
• 4 2 5
• 1 7 0 0
• 2 1 2 5 next..

4
Step 2

• Count the total decimals places in the factors

5
Step 1

• 8.5
• X2.5
• 4 2 5
• 1 7 0 0
• 2 1 2 5 next..

6
Step 3

• Give the product the total decimal places of the
  factors

7
Step 1

• 8.5
• X2.5
• 4 2 5
• 1 7 0 0
• 2 1 .2 5

8
Try These

1. 4.8 2. 3.55 x 0.5
x .05
9
Answers

1. 4.8 2. 3.55 x 0.5
x .05 2.40
0.1775
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Properties of Multiplication
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Identity Property

• The product of 1 and a number (a) is the number
  (a)
• 1(a) a

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Examples

• 1 (b) b
• 1 x 42 42

13
Zero Property

• The product of 0 and a number (a) is 0
• 0 (a) 0

14
Examples

• 0 (b) 0
• 0 x 67 0

15
Commutative Property

• Changing the order of the factors does not change
  the answer

16
Examples

• a ( b ) b ( a )
• 5 x 2 2 x 5

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Associative Property

• Changing the grouping of factors does not change
  the answer

18
Examples

• ( a b ) c a ( b c )
• ( 3 x 2 ) x 4 3 x ( 2 x 4 )

19
Try These

• Identify the property
• ( x y ) z x ( y z )
• 0 x 4 0

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Answers

• ( x y ) z x ( y z )
• Associative Property of x
• 0 x 4 0
• Zero Property