Easy Decimal Arithmetic: Move It Up! (Dividing)

Contributor: Briana Pincherri. Lesson ID: 11354

Are you ready to "move up" to dividing numbers that have decimal figures? This lesson "points" out that it's not that hard! There are simple rules (and some short videos and online practice!) to help!

categories

Middle School

subject
Math
learning style
Visual
personality style
Lion, Otter
Grade Level
Middle School (6-8)
Lesson Type
Quick Query

Lesson Plan - Get It!

Audio:

Does dividing decimals come as easily as adding, subtracting, and multiplying with decimals? Are there some crazy rules to follow when dividing with decimals? Try this lesson to find out!

GOOD NEWS!

Dividing decimals is not that tricky, either. At this point, you should have mastered adding, subtracting, and multiplying decimals with lots of practice in the previous Related Lessons in the Easy Decimal Arithmetic series found in the right-hand sidebar. It is a natural step to complete division with decimals as well. Let's jump right in to take a look!

The biggest concern with division is that there is one thing you have to look for right off the bat: whether there is a decimal in the dividend, divisor, or both. So let's take a minute to review what those terms mean.

Dividend The total number that is being divided into smaller parts

Divisor The number by which another number is divided

Quotient The answer you get when dividing one number by another

 

5

 

125

 
 

 

 
 

dividend

 

divisor

 

 

 

125

÷

5

=

 

 

 
 

dividend

 

divisor

 

 

As you can see, it doesn't matter which way it is written — the dividend is 125 because it is the total number that is being divided by something else, and 5 is the divisor because it is the number that is dividing the total.

Now that you know which number is the dividend and which number is the divisor (don't be afraid to look back up here to be reminded!), let's look at how we divide decimals:

Dividing Decimals

If the decimal is in the dividend:

  • Divide like normal, as if the decimal isn't there.
  • At the end, MOVE the decimal STRAIGHT UP into the quotient.

If the decimal is in the divisor:

  • First, move the decimal all the way to the right in the divisor until you have a whole number.
  • However many places you moved it in the divisor, you also have to move it that many places in the same direction in the dividend.
  • Then, divide like normal, and MOVE the decimal STRAIGHT UP into the answer!

Example 1:

  1.25 ÷ 5 =
     
  dividend   divisor  

 

Do the division. You can ignore the decimal.

        2 5
  5 1 . 2 5
    - 1 0  
        2 5
      - 2 5
          0

 

MOVE the decimal straight up into the answer!

0.25

Example 2:

  125 ÷ 0.5 =
     
  dividend   divisor  

 

Because the decimal is in the divisor, you need to move it until you have a whole number. In this case, just move the decimal one spot right to make it 5.

Since you moved the decimal 1 spot in the divisor, you also have to move it one spot right in the dividend too, which makes it 1250.

      2 5 0
  5 1 2 5 0
  - 1 0    
      2 5  
    - 2 5  
        0  
      - 0  
        0  

 

250

Go ahead to the next section to see just how well you understood these examples. There will be short videos to watch to see a few more division problems.

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