Common Core: 6th Grade Math : Fluently Add, Subtract, Multiply, and Divide Multi-Digit Decimals: CCSS.Math.Content.6.NS.B.3

Study concepts, example questions & explanations for Common Core: 6th Grade Math

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Example Questions

Example Question #6 : Dividing Multi Digit Decimals

Solve:

Possible Answers:

Correct answer:

Explanation:

The first thing that we want to do when dividing decimals is to turn the divisor into a whole number. We do this by moving the decimal place to the right: 

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If we move the decimal over one place in the divisor, we must also move the decimal over one place in the dividend:  

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The new division problem should look as follows:  

Screen shot 2020 10 08 at 2.48.57 pm

*Notice how we've already placed the decimal in our answer. When we divide decimals, we place the decimal directly above the decimal in the dividend, but only after we've completed the first two steps of moving the decimal point in the divisor and dividend.

Now we can divide like normal:

Screen shot 2020 10 08 at 2.48.57 pm

Think: how many times can 2 go into 4

2 can go into 4 two times so we write a 2 over the 4 in the dividend:

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Next, we multiply 2 and 2 and write that product underneath the 4 and subtract:

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Now we bring down the 0 from the dividend to make the 0 into 00.

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Think: how many times can 2 go into 0

2 can go into 0 zero times so we write a 0 over the 0 in the dividend:

Screen shot 2020 10 08 at 2.55.04 pm

Next, we multiply 2 and 0 and write that product underneath the 0 and subtract:

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Now we bring down the 9 from the dividend to make the 0 into 9.

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2 can go into 9 four times so we write a 4 over the 9 in the dividend:

Screen shot 2020 10 08 at 2.57.21 pm

Next, we multiply 2 and 4 and write that product underneath the 9 and subtract:

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Now 2 cannot be multiplied by a whole number to create a 1 so annex or add a zero to the dividend to create a number divisible by 2. We are not changing the value of the dividend by adding a zero. Bring that 0 down next to the 1 to create 10.

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Think: how many times can 2 go into 10?

2 can go into 10 five times so we write a 5 above the 0 in the dividend:

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Next, we multiply 2 and 5 and write that product underneath the 10 and subtract:

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We are left with no remainder and a final quotient of 204.5

Example Question #371 : The Number System

In the problem  which number is the dividend?

Possible Answers:

None of the answer choices are correct.

Correct answer:

Explanation:

A dividend is what you are splitting up or breaking up in a division problem. It is the amount that you want to divide up. In this problem  is the dividend. In a division problem, the dividend is listed first.

Example Question #8 : Dividing Multi Digit Decimals

Which model correctly represents  on the hundreds block?

Possible Answers:

Screen shot 2020 10 08 at 3.25.02 pm

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Correct answer:

Screen shot 2020 10 08 at 3.17.06 pm

Explanation:

Models are often used to help represent the division of decimals and help connect the related equation with a visual representation.

You need to shade a rectangle with an area of 0.24. So, shade 24 small squares, in a decimal model.

Screen shot 2020 10 08 at 3.17.06 pm

There are many rectangles with an area of 0.24. You need to shade one that has a length of 0.6.

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The missing factor is 0.4 which we can see is represented on the y-axis of the hundreds block.

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The area if a 0.4 by 0.6 rectangle is 0.24. Therefore, 0.24 ÷ 0.6 = 0.4

Example Question #9 : Dividing Multi Digit Decimals

Solve the problem using the area model provided.

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Possible Answers:

Correct answer:

Explanation:

Models are often used to help represent the division of decimals and help connect the related equation with a visual representation.

You need to shade a rectangle with an area of 0.12. So, shade 12 small squares, in a decimal model.

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There are many rectangles with an area of 0.12. You need to shade one that has a length of 0.3.

Screen shot 2020 10 08 at 3.31.33 pm

The missing factor is 0.4 which we can see is represented on the y-axis of the hundreds block.

Screen shot 2020 10 08 at 3.33.53 pm

The area if a 0.4 by 0.3 rectangle is 0.12. Therefore, 0.12 ÷ 0.3 = 0.4

Example Question #10 : Dividing Multi Digit Decimals

Which model correctly represents  on the hundreds block?

Possible Answers:

Screen shot 2020 10 08 at 3.40.32 pm

Screen shot 2020 10 08 at 3.39.27 pm

Screen shot 2020 10 08 at 3.39.57 pm

Screen shot 2020 10 08 at 3.37.18 pm

Correct answer:

Screen shot 2020 10 08 at 3.37.18 pm

Explanation:

Models are often used to help represent the division of decimals and help connect the related equation with a visual representation.

You need to shade a rectangle with an area of 0.25. So, shade 25 small squares, in a decimal model.

Screen shot 2020 10 08 at 3.37.18 pm

There are many rectangles with an area of 0.25. You need to shade one that has a length of 0.5.

Screen shot 2020 10 08 at 3.37.39 pm

The missing factor is 0.5 which we can see is represented on the y-axis of the hundreds block.

Screen shot 2020 10 08 at 3.38.00 pm

The area if a 0.5 by 0.5 rectangle is 0.25. Therefore, 0.25 ÷ 0.5 = 0.5

Example Question #1 : Multiplying Multi Digit Decimals

Find the product.

Steven bought 4 cheeseburgers to share.  Each cheeseburger costs $0.79.  How much did Steven pay for the 4 cheeseburgers?

Possible Answers:

Correct answer:

Explanation:

The easiest way to do this problem is to multiply .  

Another option is to add .  

Either way, the correct answer is .

Example Question #51 : Fluently Add, Subtract, Multiply, And Divide Multi Digit Decimals: Ccss.Math.Content.6.Ns.B.3

Multiply: 

Possible Answers:

Correct answer:

Explanation:

We ignore the decimals for the time being, multiplying:

Since, between them, the two original factors have a total of two digits to the right of their decimal points, we place the decimal point in the product so that there are two digits to the right. This yields:

Example Question #3 : Multiplying Multi Digit Decimals

Gina is recylcing bottles. She earns  for each plastic bottle she recycles and  cents for each glass bottle she recycles.

If Gina recycles  plastic bottles and  glass bottles, how much money does she earn?

Possible Answers:

Correct answer:

Explanation:

Multiply the number of plastic bottles Gina recycles by the amount she earns for each plastic bottle, then multiply the number of glass bottles she recycles by the amount she earns for each glass bottle.

 plastic bottles at  each earns 

 glass bottles at  each earns 

Add these earnings together to find Gina's total earnings.

Example Question #1 : Multiplying Multi Digit Decimals

Isaiah buys 5 snacks from the vending machine . If each snack is $1.75, how much money does Isaiah spend?

Possible Answers:

Correct answer:

Explanation:

Since each snack costs $1.75, multiply $1.75 by 5 to find the total cost:

 

Example Question #1 : Multiplying Multi Digit Decimals

Jenny is getting ready for school. She bought school supplies on a tax-free day. She bought notebooks for $1.25 each and crayons for $0.90 each. Jenny bought two more notebooks than crayons. She paid with a ten dollar bill and got $1.05 in change. How many notebooks did she buy?

Possible Answers:

3

4

1

5

2

Correct answer:

5

Explanation:

Define variables as x = number of crayons and x + 2 = number of notebooks

To find out how much she spent, we subtract her change from what she paid with: 10.00 – 1.05 = 8.95

Then we need to solve the problem cost of notebooks plus the cost of crayons equals the total cost.

1.25(x + 2) + 0.90x = 8.95 and solving for x gives 3 crayons and 5 notebooks                    

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