4-1 to 4-4 Review

Topic 4 Test Review Part 1

Lessons 4-1 through 4-4 Review

4-1: Multiply Decimals by Powers of 10

• When multiplying by a WHOLE NUMBER power of 10, the decimal point moves to the RIGHT

• When multiplying by a DECIMAL power of 10, the decimal point moves to the LEFT

• Add zeroes in blank spaces after moving the decimal point

Examples: Multiplying Decimals by Powers of 10

3.45 x 10 = 34.5
3.45 x 100 = 345
3.45 x 1,000 = 3,450 

Examples: Multiplying Decimals by Powers of 10

3.45 x 0.1 = 0.345
3.45 x 0.01 = 0.0345
3.45 x 0.001 = 0.00345

Multiple Choice

Some large envelopes are 0.085 cm thick. How thick is a stack of 100 envelopes packed on top of each other?

• 0.85 cm

• 8.5 cm

• 85 cm

• 850 cm

Multiple Choice

Tell if the number 10³

will make each equation true:

0.79 x 10³ = 790

• Yes

• No

Multiple Choice

Tell if the number 10³

will make each equation true:

0.63 x 10³ = 630

• Yes

• No

Multiple Choice

Tell if the number 10³

will make each equation true:

0.023 x 10³ = 23

• Yes

• No

Multiple Choice

Tell if the number 10³

will make each equation true:

14.5 x 10³ = 1,450

• Yes

• No

Multiple Choice

What is the product of 0.702 x 10²?

• 7.02

• 7,020

• 70.2

• 0.702

Multiple Choice

What is the product of 702 x 

 $\frac{1}{100}$ ? 

• 7.02

• 7,020

• 70.2

• 0.702

Multiple Choice

What is the product of 7.02 x  $10^3$  ?

• 7.02

• 7,020

• 70.2

• 0.702

Multiple Choice

What is the product of 702 x  $\frac{1}{10^3}$  ?

• 7.02

• 7,020

• 70.2

• 0.702

Multiple Choice

Choose Yes or No to tell if the decimal 0.29 will make each equation true.

10³ x __ = 29

• Yes

• No

Multiple Choice

Choose Yes or No to tell if the decimal 0.29 will make each equation true.

10⁰ x __ = 0.29

• Yes

• No

Multiple Choice

Choose Yes or No to tell if the decimal 0.29 will make each equation true.

10² x __ = 290

• Yes

• No

Multiple Choice

Choose Yes or No to tell if the decimal 0.29 will make each equation true.

10⁴ x __ = 2,900

• Yes

• No

4-2: Estimate the Product of a Decimal & a Whole Number

• You can estimate the product of a decimal and a whole number by using compatible numbers and rounding. 

  
  

• Remember, when estimating you always want to choose numbers that are as close as possible to the original numbers, but are still easy to compute.

4-3: Use Models to Multiply a Decimal and a Whole Number

• Shade in the same number of squares as the decimal number, as many times as the whole number

• Remember, 1 whole grid = 1

• One column or row = 0.1

• One square = 0.01

Multiple Choice

Which equation does the grid represent?

• 1.6 x 0.3

• 2.6 x 0.3

• 16 x 3

• 0.16 x 0.03

Multiple Choice

What is the product of 1.6 x 0.3? Use the grid to help.

• 0.48 square mile

• 4.8 square mile

• 48 square mile

• 480 square mile

4-4: Multiply a Decimal by a Whole Number

• The steps used in multiplying a decimal by a whole number are similar to the steps used in multiplying a whole number by a whole number.

• Remember to take out the decimal point and multiply as normal, then add the decimal point back in

• Remember that multiply by 0.5 is like saying "half of"!

Multiple Choice

Solve:

6 x 0.5

• 30

• 0.3

• 0.03

• 3

Multiple Choice

Solve:

0.6 x 0.5

• 30

• 0.3

• 0.03

• 3

Multiple Choice

Solve:

60 x 0.5

• 30

• 0.3

• 0.03

• 3

Multiple Choice

Solve:

0.06 x 0.5

• 30

• 0.3

• 0.03

• 3

Fill in the Blanks