Dividing Decimals (3-4)

Dividing Decimals

Vocabulary

Integers - A set of whole numbers and their opposites.

Divisor - The quantity by which another quantity is to be divided (the number outside).

Dividend - A quantity to be divided (the number inside).

Quotient -  The result (answer) of the division of one quantity by another.

When you divide two numbers, you can multiply both numbers by the same power of ten without changing the final answer. Example: 0.6 / 0.3 = 2, multiply 0.6 by 10 = 6; multiply 0.3 by 10 = 3

...6/3 = 2  Notice, it is the same answer.

To divide decimal numbers:

1. If the divisor is not a whole number, move decimal point to right to make it a whole number and move decimal point in dividend the same number of places.
2. Divide as usual. ...
3. Put decimal point directly above decimal point in the dividend.
4. Check your answer.

Dividing Decimals

Quick method: use Long Division without the decimal point,
then re-insert the decimal point in the answer.

Dividing a Decimal Number by a Whole Number

To divide a decimal number by a whole number:

• Use Division or Long Division (ignoring the decimal point)
• Then put the decimal point in the same spot as the dividend (the number being divided)
  

Example: Divide 9.1 by 7

Ignore the decimal point and use Long Division:

13 7 )91    9    7    21    21     0

Put the decimal point in the answer directly above the decimal point in the dividend:

1.3 7 )9.1

The answer is 1.3

Dividing by a Decimal Number

But what if we want to divide by a Decimal Number?
The trick is to change the number we are dividing by to a whole number first, by shifting the decimal point of both numbers to the right:

Now we are dividing by a whole number, and can continue as normal.
It is safe to do this if we remember to shift the decimal point of both numbers the same number of places.

Example: Divide 6.4 by 0.4

We are not dividing by a whole number, so we need to move the decimal point so we are dividing by a whole number:

move 1
6.4		64
0.4		4
move 1

6.4/0.4 is exactly the same as 64/4,
as we moved the decimal point of both numbers.

Now we can calculate:

64 / 4 = 16

So the answer is:

6.4 / 0.4 = 16

Are there really 16 lots of 0.4 in 6.4? Let's see:

Example: Divide 5.39 by 1.1

Move the decimal point so that we are dividing by a whole number:

move 1
5.39		53.9
1.1		11
move 1

We are now dividing by a whole number, so we can proceed:
Ignore the decimal point and use Long Division:

049 11 )539     5     0     53     44      99      99       0

Put the decimal point in the answer directly above the decimal point in the dividend:

04.9 11 )53.9

The answer is 4.9

 https://www.mathsisfun.com/dividing-decimals.html

Video Help

https://www.youtube.com/watch?v=S0uuK7SQcA8

https://www.youtube.com/watch?v=0onPTEpShPU

https://www.youtube.com/watch?v=2K_7L44RVD8