Multiplying Decimals

1
Multiplying Decimals

• Lesson 1-7

2
To Multiply

• You do not line up the factors by the decimal.
• Instead, place the number with more digits on
  top.
• Line up the other number underneath, at the
  right.
• Multiply
• Count the number of decimal places (from the
  right) in each factor.
• Use the total number of decimal places in your
  two factors to place the decimal in your product.

3
Example 5.63 x 3.7
1
2
4
5.63
two
x
3.7
one
1
1
1
4
39
1
0
9
8
16

1
3
8
0
2
.
three
4
Example 0.53 x 2.618
2.618 has more digits (4) than 0.53 (3), so it
goes on top.
x?
4
3
Decimal Places
2
1
2.618
three
0.53
x
two
1
4
5
8
7
0
0
9
0
13
00
0
0
0
0

.
4
5
7
8
3
1
five
5
Try This 6.5 x 15.3
1
3
1
2
15.3
one
6.5
x
one
1
5
6
7
0
8
1
9

.
5
4
9
9
two
6
Multiplication Properties
Commutative Property of Multiplication Factors
can be multiplied in any order. Example 12 x 5
5 x 12
Associative Property of Multiplication Factors
can be grouped in any way. Example (2 x 3) x 5
2 x (3 x 5)
Identity Property of Multiplication The product
of any number and one is that number. Example 18
x 1 18
7
Homework Time
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