4–9
Name
Date
Decimal Movement
Looking at patterns in the movement of the decimal point can help you estimate decimal
products.
Multiply to complete the table below.
ⴛ
800
80
8
0.8
0.08
0.008
400
40
4
0.4
0.04
0.004
1.
Describe the patterns you see in the table.
2.
Use the patterns you found in the table to complete the multiplication sentences.
a. 8,000
4,000 80,000 b.
3,200,000,000
400,000 320,000,000,000
3.
0.0004 0.0008 0.00004 0.0000000032
0.000008 0.000000000032
Connect It Explain how you can use the patterns you found in the table to help you
multiply decimals.
4–9
Name
Date
Decimal Movement
Looking at patterns in the movement of the decimal point can help you estimate decimal
products.
Multiply to complete the table below.
ⴛ
800
400
40
4
0.4
0.04
0.004
1.
80
320,000 32,000
32,000 3,200
3,200
320
320
32
32
3.2
3.2
0.32
8
0.8
3,200
320
32
3.2
0.32
0.032
0.08
0.008
320
32
3.2
32
3.2
0.32
3.2
0.32
0.032
0.32
0.032
0.0032
0.032 0.0032 0.00032
0.0032 0.00032 0.000032
Describe the patterns you see in the table. Sample
answer:
All products contain basic fact 4 ⴛ 8 ⴝ 32; as you go
down a column, products decrease by a power of ten; as
you go across a row, products decrease by a power of ten.
2.
Use the patterns you found in the table to complete the multiplication sentences.
a. 8,000
3.
4,000 32,000,000
b.
0.0004 0.0008 0.00000032
80,000 40,000 3,200,000,000
0.00004 0.00008 0.0000000032
800,000 400,000 320,000,000,000
0.000004 0.000008 0.000000000032
Connect It Explain how you can use the patterns you found in the table to help you
multiply decimals.
Sample answer: First find the product of the basic
fact, then move the decimal point to the left based on
the place value of the factors.