Lesson 4 — Activity 5: Dividing Decimals

If you can divide whole numbers, then you can divide numbers with decimals. It uses the same division process!

Remember you learned that to multiply decimal numbers, you simply ignored the decimal point until you had finished multiplying all of the numbers. When dividing by a decimal number, deal with the decimal point before you do anything else. What you do changes depending on whether you are dividing by a whole number or a decimal number. Once you have taken care of the decimal, you then simply follow the procedure for doing division of whole numbers.

Steps for dividing decimals:

Place the decimal point directly above the decimal point in the dividend.

Divide the numbers as if there were no decimals.

Estimate (guess) what number might be tried to divide into the dividend.

Multiply your guess.

Subtract the two numbers.

Bring down the next number.

Repeat the process again until you get an answer.

Check your answer by multiplying the answer by the number you divided by.

The first and most important step to remember when dividing by a decimal number is to convert the number you are dividing by (divisor) to a whole number.

Decimals are another form of writing fractions (which you will learn about in a later lesson), but the decimal point takes the place of the line that separates the numerator and the denominator. This means that whatever change is made to the divisor, must also be made to the dividend.

This is really quite simple as is shown below.

• Shift the decimal point in the divisor (0.53) to the right until it is placed at the end.
• The divisor is now a whole number (53).
• Remember, you must do the same thing to the number into which you are dividing (6.625). 
• This means the decimal point has to be moved two places to the right.

The problem now looks like this, and because you are dividing by a whole number, you can continue dividing as normal.

           12.5   
53 )662.5
       -53
        132
      -106
        265
      -265
             0

It is safe to do this if you remember to shift the decimal point of both numbers the same number of places.

Click on the Play button below to watch a video on how to divide decimal numbers.

  Self-check!

Digging Deeper!

Click here to go to the Study Jams website to learn more about dividing decimals. When you get to the site, click on "Step by Step" to begin. When you have finished, click on the "Try It!" link to practise dividing decimals!

Click here for tips on dividing decimals by 10, 100, and 1,000!