Muliply/ Divide Decimals Wk 15

Rules for Multiplying Decimals

• First multiply as if there is no decimal.

• Next, count the number of digits after the decimal in each factor.

• Finally, put the same number of digits behind the decimal in the product

Multiple Choice

What is the first rule for multiplying decimals?

• Line up decimals

• Multiply as if there is no decimal

• Add digits behind the decimals

• Always move decimal to the left in the product

Reorder

Place rules in the correct order

• Multiply as if there is no decimal

• Count the number of digits after the decimal in each factor

• Put the same number of digits behind the decimal in the product

1

2

3

• 1
• 2
• 3

​total of 2 decimal points to the left

Multiple Choice

If you multiply 3.46 by 2.4, how many digits will be behind the decimal in your answer? OR how many decimal places must you move?

• 1

• 4

• 2

• 3

Multiple Choice

Do the decimal points need to the lined up when we MULTIPLY decimals?

• Yes

• No

Multiple Choice

390 x 0.01 = ?

• 390

• 39

• 3.9

Multiple Choice

0.9 x 0.8 = ___________

• 0.63

• 0.72

• 7.2

• 0.063

Multiple Choice

8 x 0.004 = ____________

• 0.0032

• 0.32

• 3.2

• 0.032

Multiple Choice

0.6 x 8 = __________

• 4.8

• 0.048

• 0.48

• 6.4

Dividing Decimals

WATCH THE VIDEO (it is short)

Some Vocabulary Review!!

Dividend Divided by Divisor Equals Quotient

Dividend Divided by Divisor Equals Quotient

Dividend Divided by Divisor Equals Quotient

Labelling

Use the correct vocabulary to complete the picture.

Drag labels to their correct position on the image

term 2

product

factor 2

sum

quotient

dividend

divisor

addend 1

factor 1

difference

Multiple Choice

Which number is the divisor?

14 ÷ 7 = 2

• 14

• 7

• 2

Multiple Choice

Which number is the quotient?

14 ÷ 7 = 2

• 14

• 7

• 2

Multiple Choice

Which number is the dividend?

14 ÷ 7 = 2

• 14

• 7

• 2

If the divisor has a decimal, you must multiply the divisor by a power of 10 to make it a whole number.

Then you must multiply the dividend by the same power of 10

Example: 17.52 ÷ 1.2

How do you just "MOVE A DECIMAL?" MR DL

Multiply by power of ten 10
The DECIMAL MOVES RIGHT
3.12 x 10 = 31.2

or

Divide by a power of 10
The DECIMAL MOVES LEFT
3.12 / 10 = 0.312

Multiple Choice

When you multiply by the power of 10 will the decimal move to the right or to the left?

• Right

• Left

Multiple Choice

34.2 X 1000

• 34.22

• 3.42

• 34,200

Multiple Choice

86.76 X 10

• 867.6

• 86.76

• 8.676

• 86.760

Multiple Choice

2 x 0.67 = ?

• 134

• 1.34

• 13.4

• .134

Math Response

0.3 x 0.5

Type answer here

Correct Answer: 0.15

Deg^°

Rad

Math Response

$$4\cdot0.03=$$

Type answer here

Correct Answer: 0.12

Deg^°

Rad

Steps for Dividing Decimals

First, make your divisor a WHOLE number by moving the decimal to the right.

Next, move the decimal in the dividend the SAME number of places.

Then, move the DECIMAL up to the quotient.

Multiple Choice

Which of these expressions is equivalent to $$8\div0.2$$ ?

• $$0.8\div2$$

• $$8\div2$$

• $$80\div2$$

• $$800\div2$$

Multiple Choice

Find the equivalent expression for $$21.98\div3.4$$ .

• $$2.198\div34$$

• $$21.98\div34$$

• $$219.8\div34$$

• $$2,198\div34$$

Math Response

Dividing decimal by whole number: What is the result of 3.6 ÷ 4?

Type answer here

Correct Answer: 0.9

Deg^°

Rad

Multiple Choice

What is the final answer in this problem?

• 13.3

• 13

• 13.7

• 13.5

Multiple Choice

This division problem will turn into which problem below?

Multiple Choice

This division problem will turn into which problem below?

Multiple Choice

$$9.6\ \div3$$  

• 32

• 3.2

• 0.32

• 320

Steps to Dividing with Decimal

• Step 1: Move the decimal point in the divisor to make it a whole number.

• Step 2: Move the decimal point in the dividend the same number of spaces.

• Step 3: Divide

• Step 4: Line up your decimals

Multiple Choice

What do I need to do first in this problem? 

$$4.29\div.11$$

• Divide like normal

• Move the decimal two times to the left

• Move the answer two times to the right in the divisor and two times in the dividend