Multiplying and dividing fractions

Front

Galveston County area: 378 sq miles. Divided into sections of 1/6 sq mile. How many sections?

Back

2,268 sections

Answer explanation

You are dividing the county into 1/6 sections. Whatever is being divided goes first in the equation.

378 divided by 1/6 sections =

Put 378 over 1 to make it a "visible" fraction.

(**invisible math - the one is always there, just invisible**).

Then flip the 2nd number (1/6 to 6/1) and multiply straight across.

378/1 x 6/1 = 2,268/1

Simplify 2,268/1 = 2,268

Front

Nancy has a gallon-sized container in which she collects rainwater. Last weeks’ rain filled 1/9 of the container. Nancy wants to water 5 of her plants with this rainwater. Each plant will be watered with the same amount of rainwater. What amount of rainwater will each plant receive?

Back

Answer explanation

You are dividing the amount of rain collected (1/9) by the 5 plants.

1/9 divided by 5 = 1/45

Put the 5 over one to make a visible fraction.

(**invisible math: the one is always there, you just can't see it.)

1/9 divided 5/1=

Flip the second number and multiply straight across.

1/9 x 1/5 = 1/45

Tags

CCSS.5.NF.B.7A

CCSS.5.NF.B.7C

Front

Back

Answer explanation

Put 30 over one to make it a visible fraction.

1/5 divided by 30/1

Flip the second number and multiply straight across.

1/5 x 1/30 = 1/150

Tags

CCSS.5.NF.B.7A

CCSS.5.NF.B.7C

Front

Back

6 days

Answer explanation

Dividing

3 cups divided by 1/2 cup each day.

Put a one under the 3 to make it a visible fraction.

3/1 divided by 1/2 = 6

Flip the second number and multiply straight across.

3/1 x 2/1 = 6/1

Simplify 6/1 = 6

Tags

CCSS.5.NF.B.7B

CCSS.5.NF.B.7C

Front

Back

12

Answer explanation

Divide

18 cups divided by 1/8 cup

Put 1 under 18 to make it a visible fraction.

18/1 divided by 1/8 = 144

Flip the second number and multiply straight across.

18/1 x 8/1 = 144/1 = 144

The question asked how many dozen. Your answer gave you how many cookies.

Divide 144 by 12 to get how many dozen because there are 12 in a dozen.

144 divided by 12 = 12

So, 12 dozen cookies can be made from 18 cups of dough if each cookie is 1/8 cup.

Front

Back

Answer explanation

Multiply

7 boxes and each box has 3/4 in it.

Count all the 3/4 and put them together in boxes with a total of 4 parts.

Your answer is 5 wholes and 1/4

Tags

CCSS.5.NF.B.4B

Front

Back

Answer explanation

You have 15 bars in 5 groups of 3.

3 of the 5 groups are shaded in.

Tags

CCSS.5.NF.B.4A

Front

Back

Answer explanation

3/4 x 4 = 12/4

the picture shows 4 groups of 3/4 and then those groups put together, making 3 whole groups.

12/4 is improper

To simplify you divide 4 into 12 and that = 3

Tags

CCSS.4.NF.B.4A

CCSS.4.NF.B.4B

Front

Julissa was allowed to spend 3/4 of her allowance at the mall. Of that money, she spent 1/2 of it on a purse. What part of her allowance did she spend on a purse?

Back

3/8

Answer explanation

Multiply:

Clue phrase:

1/2 OF it (it is the money)

Clue word OF

1/2 OF the money.

What do you know:

She is spending 3/4 of her allowance at

the mall.

She is spending 1/2 OF that 3/4 on a purse.

OF tells you to multiply

1/2 x 3/4 = 3/8

Tags

CCSS.5.NF.B.6

Front

Back

Answer explanation

Multiply:

What you know:

1 1/2 pizza left over

John's dad ate 3/4 OF the leftovers

Meaning he ate 3/4 OF 1 1/2

Clue words

OF

change 1 1/2 into an improper fraction.

(multiply 1x2 then add 1 and put the answer over 2) 3/2

3/2 x 3/4 = 9/8

simplify 9/8

8 divides into 9 one time (whole number) with one left over (numerator) 8 stays the denominator.

9/8 = 1 1/8

Tags

CCSS.7.NS.A.3