topic badge
India
Class VII

Long division - dividing 3 digit numbers

Lesson

Dividing whole numbers with remainder

We have seen how dividing 3 digit numbers can result in remainder, if we are not able to share our totally out equally. We can write the remainder as a decimal, and we have seen how to do this by breaking our total into smaller numbers and dividing them separately, or using short division. This would be similar to exchanging a $\$20$$20 note for four $\$5$$5 notes, so we could share the amount equally between four people.

Let's look at how we can solve the same type of problem, using long division. You'll see we think about how a fraction can be written as a decimal, to help us express our remainder in decimal form.

In Video  1, we solve a division using long division, resulting in a decimal answer. To do this we are going to:

  • estimate our answer,
  • solve the long division, then 
  • check if our final answer seems reasonable by comparing our answer to our estimate.

 

Long division with hundredths

Even though long division might look trickier, it's actually easier to solve. Since we show every calculation, we can see what we have done all the way through.

In Video 2, we use this same approach to work out a long division problem that results in hundredths as our answer.

Remember!
  • Estimate the answer.
  • Solve the long division. 
  • Check that the solution seems reasonable.

 

Worked examples

Question 1

We want to find $879\div5$879÷​5.

  1. Choose the most reasonable estimate for $879\div5$879÷​5.

    $176$176

    A

    $276$276

    B

    $70$70

    C

    $2$2

    D
  2. Fill in the multiplication table for $5$5.

    $2$2 $10$10
    $3$3 $15$15
    $4$4 $\editable{}$
    $5$5 $\editable{}$
    $6$6 $\editable{}$
    $7$7 $35$35
    $8$8 $\editable{}$
    $9$9 $\editable{}$
  3. Complete the long division to find $879\div5$879÷​5.

      $\editable{}$ $\editable{}$ $\editable{}$ $.$. $\editable{}$
    $5$5   $8$8 $7$7 $9$9 $.$. $0$0
      $\editable{}$  
      $\editable{}$ $\editable{}$  
      $\editable{}$ $\editable{}$  
      $\editable{}$ $\editable{}$  
      $\editable{}$ $\editable{}$  
      $\editable{}$   $\editable{}$
      $\editable{}$   $\editable{}$
      $\editable{}$

Question 2

We want to find $620\div8$620÷​8.

  1. Choose the most reasonable estimate for $620\div8$620÷​8.

    $178$178

    A

    $1$1

    B

    $78$78

    C

    $700$700

    D
  2. Fill in the multiplication table for $8$8.

    $2$2 $16$16
    $3$3 $24$24
    $4$4 $\editable{}$
    $5$5 $\editable{}$
    $6$6 $\editable{}$
    $7$7 $56$56
    $8$8 $\editable{}$
    $9$9 $\editable{}$
  3. Complete the long division to find $620\div8$620÷​8.

        $\editable{}$ $\editable{}$ $.$. $\editable{}$
    $8$8   $6$6 $2$2 $0$0 $.$. $0$0
      $\editable{}$ $\editable{}$  
      $\editable{}$ $\editable{}$  
      $\editable{}$ $\editable{}$  
      $\editable{}$   $\editable{}$
      $\editable{}$   $\editable{}$
      $\editable{}$

Question 3

We want to find $504\div16$504÷​16.

  1. Choose the most reasonable estimate for $504\div16$504÷​16.

    $300$300

    A

    $31$31

    B

    $132$132

    C

    $3$3

    D
  2. Fill in the multiplication table for $16$16.

    $2$2 $32$32
    $3$3 $48$48
    $4$4 $\editable{}$
    $5$5 $\editable{}$
    $6$6 $\editable{}$
    $7$7 $112$112
    $8$8 $\editable{}$
    $9$9 $\editable{}$
  3. Complete the long division to find $504\div16$504÷​16.

          $\editable{}$ $\editable{}$ $.$. $\editable{}$
    $16$16   $5$5 $0$0 $4$4 $.$. $0$0
      $\editable{}$ $\editable{}$  
      $\editable{}$ $\editable{}$  
      $\editable{}$ $\editable{}$  
      $\editable{}$   $\editable{}$
      $\editable{}$   $\editable{}$
      $\editable{}$

Outcomes

7.NS.FRN.10

Multiplication and division of decimal fractions

What is Mathspace

About Mathspace