Multiplying Decimals

Multiplying Decimals

Multiplying by Powers of 10

• 2 x 10 = 20

• 2 x 100 = 200

• 2 x 1000 = 2000

• 2 x 10000 = 20000

Multiple Choice

What do you do to the decimal point when you multiply by a power of 10?

• Move the decimal point once to the right for each zero.

• Move the decimal point once to the left for each zero.

How does this work for decimals?

• 3.25 x 10 = 32.5

• 3.25 x 100 = 325

• 3.25 x 1000 = 3,250

Multiple Choice

Multiply 62.397 by 10

• 6239.7

• 623.97

• 62.40

• 62397.0

Multiple Choice

0.0867 x 100

• 86.7
• 8.67
• 0.867

Multiple Choice

4.23 x 10

• 42.3
• 423
• 4.23

Multiple Choice

0.62 x 100

• 6.2
• 62
• .062

Multiple Choice

5.1 x 100

• 510

• 51

• .51

What about multiplying by a decimal?

• 56 x 0.1 = 5.6

• 56 x 0.01 = .56

• 56 x 0.001 = .056

Multiplying by a decimal is like dividing by a power of 10 and causes the decimal point to move to the left.

Multiple Choice

17.8 x 0.01

• 0.178
• 0.0178
• 178
• 1.78

Multiple Choice

5.02 x 0.1

• 5.02
• 50.2
• 0.0502
• 0.502

Multiple Choice

214.5 x 0.001

• 2,145
• 2.145
• 0.2145
• 0.02145

Multiple Choice

324 x 0.1

• 0.324
• 3.24
• 32.4
• 324

Rules for Multiplying Decimals

Multiple Choice

If 4 x 8 = 32 then 0.4 x 8 =

• 32

• 3.2

• 0.32

• 320

Multiple Choice

If 2 x 6 = 12 then 0.2 x 0.6 =

• 12

• 1.2

• 0.12

• 0.012

Multiple Choice

If 4 x 6 = 24 then .04 x .06 =

• 24

• 2.4

• .24

• .024

• .0024

Multiple Choice

If 5 x 9 is 45 then 5 x 0.009 =

• 45

• 4.5

• 0.45

• 0.045

• 0.0045

Multiple Choice

If 3 x 10 is 30 then .03 x .1 =

• 30

• 3.0

• 0.3

• 0.03

• 0.003

Poll

How do you feel about Multiplying Decimals?

• Great!

• Good

• Okay

• Unsure

• Bad