Multiplying Decimals

Estimate the Product

100

Estimate the Product

5.2 x 3.7=

What is

20

200

Estimate the product

1.07 x 0.97=

What is

1

300

Estimate the product

12.34 x 5.12=

What is

60

400

Estimate the product

9.567 x 5.454

What is 

50

500

Estimate the product

11.123 x 4.321

What is

44

Place the decimal point

100

What is the correct product

2.56 x 1.14

a. 0.256

b. 2.56

c. 25.6

d. 256

What is 

2.56

200

What is the correct product

17.56 x 6.3=

a. 11.0628

b. 110.628

c. 1106.28

What is 

110.628

300

what is the correct product

41.2 x 6.78

a. 279.336

b. 2793.36

c. 27.936

What is

279.336

400

What is the correct product

15.3x 15.3=

a. 2340.9

b. 234.09

c. 23.409

What is

234.09

500

How can you solve these with mental math?

What is

Estimate each factor to the nearest whole and multiply

Write a related whole number equation to solve

100

Solve by writing a related whole number equation

0.3 x 0.4 =

What is

3 x 4 = 12

12/100= 0.12

0.3 x 0.4=0.12

200

Solve by writing a related whole number equation

0.05 x 0.2=

What is

5 x 2 = 10

10/100= 0.010

0.05 x 0.2= 0.010

300

Solve by writing a related whole number equation

0.9 x 0.03=

What is

9x3=27

27/1000=0.027

0.9x 0.03= 0.027

400

Solve by writing a related whole number equation

0.6x0.8=

What is

6 x 8= 48

48/100= 0.48

0.6x0.8=0.48

500

Explain the strategy for writing a related whole number equation to solve decimal multiplication

1. multiply each factor by a power of ten to make it a whole number.

2. multiply the whole numbers

3. divide the product of the whole number multiplication by the power of ten you increased the factors by. (if you multiplied one factor by ten, and the other by 100- you increased the factors 1000x's so you would need to divide by 1000.

Area Model

100

Use the area model to solve

1.4x2.6=

What is

3.64

200

Use the area model to solve

2.46 x 3.2=

What is

7.872

300

Use the area model to solve

5.55 x 4.5=

What is

24.975

400

Use the area model to solve

1.67 x 2.75

What is

4.5925

500

Use the area model to solve

2.46 x 6.32=

What is

15.5472

Converting to fractions

100

Solve by converting to fractions

0.3 x 0.4 =

What is

3/10 x 4/10 = 12/100

12/100=0.12

200

Solve by converting to fractions

0.05 x 0.03=

What is

5/100 x 3/100= 15/10000

15/10000= 0.0015

300

Solve by converting to fractions

0.15 x 0.3=

What is

15/100 x 3/10= 45/1000

45/1000=0.045

400

Solve by converting to fractions

0.40 x 0.2=

What is

40/100 x 2/10= 80/1000

80/1000- 0.080

500

How can you use fractions to solve decimal multiplication problems?

What is

convert each decimal factor to a fraction

multiply the fractions across

convert the product to a decimal number