Multiplying and Dividing Decimals

Multiplying and Dividing Decimals

Add (+) or Subtract (-) with decimals

• Find the decimal

• Line up the decimals

• Fill in the empty spots with zero

• Add or Subtract

• Bring down the decimal in your answer

Multiplying ( $\times$  ) with decimals

• The number with the most digits goes on top

• Decimals do not have to line up

• Multiply like normal

• Count how many places in the first number the decimal is moved over

• Count how many places in the 2nd number the decimal is moved over

• This is how many places you move the decimal in your answer

Dividing ( $\div$ ) with Decimals

• Divisor cannot have a decimal

• Move the divisor decimal so it is a whole number

• Move the same amount of places in the dividend

• Place a decimal straight up where you write your answer 

• Divide like normal

Multiple Choice

When you add two decimal numbers, you do not need to line up the decimal points.

• True

• False

Multiple Choice

When you multiply two decimal numbers, you line up the digits not the decimal points.

• True

• False

Multiple Choice

When you divide two decimal numbers, the divisor cannot have a decimal.

• True

• False

Multiple Choice

Which statement about

 $6.45\ \div0.5$  is true?

• The dividend is a whole number.

• The divisor should become 5 before you divide

• The product does not have a hundreds place.

Story Problems with Decimals

• Read the problem carefully!

• Look for clue words!

• Follow the Rules for Decimal Operations!

• Check to make sure your answer makes sense!

Multiple Choice

Alex is buying groceries. He buys milk for $2.95, Takis for $2.68, and Mt. Dew for $7.98. What will his total be before bottle deposit?

To solve this problem you should...

• add

• subtract

More Practice

Remember your rules!!

Fill in the Blank

Multiply. Do not round your answer. Be sure to include a decimal point in your answer.

 $2.5\ \times12.36$  

Fill in the Blank

Divide.

 $4.530\ \div1.5$  

Fill in the Blank

Add

 $3.25\ +14.1\ +3$  

Fill in the Blank

Subtract

 $15.56\ -\ 1.18$  

Multiple Choice

Allison had $180.47 in her checking account. She bought groceries $75.11 and gas for $29.64. How far below $100.00 is her account?

To solve this problem you should ...

• Subtract 100.00 from 180.00

• Add all the numbers

• Subtract the amount for groceries and gas from 180.47 and then subtract that amount from 100

Multiple Choice

The walking club has completed 4 out of 5 walks. They have a goal of walking 20 miles. They walked 2.6 miles, 3.8 miles, 5.6 miles, and 3.1 miles. How many miles do they need to walk to make their goal?

To solve this problem you should ...

• Subtract each walk from 20

• Add the walks and subtract from 20

• Either way will work