Multiplying Decimals

Powers of 10

100

2.3 x 10³

2,300

200

6.8 x 10⁴

68,000

300

3.4 x 10⁵

340,000

400

2.89 x 10⁴

28,900

500

Give 2 expressions using 10^x to represent 4,500. 

4.5 x 10³ and 45 x 10²

Estimation/Patterns

100

Estimate 4.2 x 10.89

4 x 11 = 44

200

Estimate 9.7 x 66

660 or 700

300

Find the missing product

1.4 x 99 = _______

14 x 99 = 1,386

138.6

400

Find the missing product

2.4 x 4.5 = 10.8

24 x 4.5 = ______

108

500

Find the missing product

6.3 x 2.3 = ______ (a)

63 x 2.3 = ______ (b)

63 x 23 = 1,449

a. 14.49

b. 144.9

Multiply - Using an Area Model if needed

100

0.6 x 0.8

0.48

200

1.7 x 3.9

6.63

300

2.7 x 3.5

9.45

400

4.2 x 0.9

3.78

500

2.32 x 0.71

1.6472

Multiply Mentally

100

0.5 x 5

2.5

200

7 x 0.4

2.8

300

1.1 x 3

3.3

400

0.8 x 0.9

0.72

500

0.12 x 0.3

0.036

Word Problems

100

Pokemon cards cost $2.95 per pack. If Alex buys 5 packs, about how much does he spend?

3 x 5 = $15

200

A recipe calls for 0.25 cups of sugar per serving. If you are making 8 servings, how much sugar do you need?

(0.25 \times 8 = 2). You need 2 cups of sugar.

300

A bottle of juice contains 1.2 liters. If you buy 4 bottles, how many liters of juice do you have in total?

(1.2 \times 4 = 4.8). You have 4.8 liters of juice in total.

400

A car travels 0.75 kilometers in one minute. How far will it travel in 6.5 minutes?

(0.75 \times 6.5 = 4.875). The car will travel 4.88 kilometers.

500

Sarah bought 3.5 meters of string to make bracelets. Each meter costs $2.75. How much did Sarah spend on the string?

Solution: (3.5 \times 2.75 = 9.625). Sarah spent $9.63 on the string.