4-5 to 4-9 Review

Topic 4 Test Review Part 2

Review for Lessons 4-5 to 4-9

4-5: Use Models to Multiply a Decimal and a Decimal

• Remember, for one decimal factor you will shade columns

• For the other decimal factor, you will shade rows

Multiple Choice

Caden colored in the decimal grid shown. Which expression shows the area of the grid Caden colored?

• 0.04 x 0.05

• 0.04 x 0.5

• 0.4 x 0.5

• 0.4 x 0.05

4-6: Multiply Decimals Using Partial Products

• Rememnber, this basically means separating the numbers into whole number and decimal parts, and multiplying each part

Example: Multiply Decimals Using Partial Products

Separate Whole Numbers and Decimals and multiply using the Box Method. Then add each partial product.

Here is another example.

Multiple Select

What are the partial products of 5.8 x 1.3? Choose all partial products.

• 1 x 5 = 5

• 1 x 0.8 = 0.8

• 3 x 5 = 15

• 0.3 x 5 = 1.5

• 0.3 x 0.8 = 0.24

Fill in the Blanks

4-7: Use Properties to Multiply Decimals

• You can turn decimals into fractions and regroup to multiply whole numbers x whole number and fractions x fractions, then convert the product back into a decimal

Take a look at this example.

Multiple Select

Choose all the expressions that are equal to 0.48 x 0.3

• $\frac{48}{100}\ \times\ \frac{3}{100}$

• $\frac{3}{10}\times\frac{48}{100}$

• $\frac{48}{100}\times\frac{30}{100}$

• $\frac{3}{100}\times\frac{48}{100}$

• $\frac{48}{100}\times\frac{3}{10}$

Multiple Select

Choose all the expressions that are equal to 0.8 x 0.07

• $\frac{8}{10}\times\frac{7}{100}$

• $\frac{80}{100}\times\frac{7}{10}$

• $\frac{8}{10}\times\frac{7}{10}$

• $\frac{7}{100}\times\frac{80}{100}$

• $\frac{7}{100}\times\frac{8}{100}$

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 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

4-8: Use Number Sense to Multiply Decimals

• Estimate first

• Use your estimation to determine where the decimal point should be placed in the product

Multiple Choice

A small business plans to order carpet for 4 identical offices. The floor of each office is 7.2 feet long and 5.8 feet wide.

In the problem above - where should the decimal point be in the exact total area?

16704 square feet

• 1.6704 square feet

• 16.704 square feet

• 167.04 square feet

• 1,670.4 square feet

• 16,704 square feet

Multiple Choice

Without doing the multiplication, match the expression with the correct product. Use number sense.

6.32 x 0.15

• 26.52

• 0.948

• 21.456

• 38.512

Multiple Choice

Without doing the multiplication, match the expression with the correct product. Use number sense.

7.45 x 2.88

• 26.52

• 0.948

• 21.456

• 38.512

Multiple Choice

Without doing the multiplication, match the expression with the correct product. Use number sense.

8.16 x 3.25

• 26.52

• 0.948

• 21.456

• 38.512

Multiple Choice

Without doing the multiplication, match the expression with the correct product. Use number sense.

9.28 x 4.15

• 26.52

• 0.948

• 21.456

• 38.512

4-9: Multiply Decimals

• Multiplying decimals is similar to multiplying whole numbers

• Use the standard algorithm, and take out the decimals to multiply

• Then, add the decimal point back in to the product by counting the number of decimal places in the factors