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Find the Common Denominator easily with this Step by Step approach

If your child can find the common denominator of fractions, they will be able to do anything they are asked in the Kindergarten through sixth grade math fractions curriculum. This includes;

Adding & subtracting fractions

multiplying & Dividing Fractions

Comparing Fractions

The Condensed Step by Step Approach

In this section, I offer you the steps involved to finding the Denominator Common to two fractions. In the next section you will find an expansion of each step explaining how and why it occurs.

So let's get to it!

Step 1: Create table and enter fractions.

Step 2: Multiply Denominators and enter value in table for both fractions in the 'New Fractions Section'.

Step 3: Multiply Numerator 1 by Denominator 2 and enter the value in 'New Fraction Numerator 1' section

Step 4:Multiply Numerator 2 by Denominator 1 and enter the value in 'New Fraction Numerator 2' section.

Step 5:Do whatever was requested in the question

How and why does this method work?.

I have to admit that when it comes to taking things step by step, I can take things a little too far! Everything has to be maped out in steps. And of course there has to be back up steps, if one of my steps doesn't work!

I realise this can seem quite painful at times. However this method has served me well. I also feel, if a child learns everything in a step by step manner and understands why each step occurs, they will have a greater chance of remembering what they learn.

So here is a detailed approach of the above list of steps.

The Detailed Step by Step Approach: How to find the Common Denominator.

We are going to use the general fractions to establish a rule to find the common denominator for any and every set of fractions.

Step 1 - Draw table and enter original fractions.

Why? To stay absolutely visually organized at all times. Disorganized work is most math students worst enemy. Keep your work organized and tidy at all times!

Step 2 - Multiply Denominators to get NEW Fraction Denominator and enter into table.

Our denominators are b & d.

b x d = bd (Our New Denominator)

Why? Because a denominator common to two fractions is a number that both denominators divide equally into.

Step 3: Find New Numerator 1

Multiply numerator of original fraction 1, by denominator of original fraction 2. Enter your result as New Fraction 1 Numerator.

Looking at the table we can see that numerator 1 and denominator 2 are a & d

a x d = ad (Our New Fraction 1 Numberator)

Step 4: Find New Numerator 2

Multiply numerator of original fraction 2, by denominator of original fraction 1. Enter your result as New Fraction 2 Numerator.
Looking at the table we can see that numerator 2 and denominator 1 are c & b

c x b = cb (Our New Fraction 2 Numberator)

Why do Steps 3 and 4 work?

Why does this work? Haven't we changed the fractions? YES we have changed the fractions, but we have NOT changed the VALUE of the fractions. The original fractions and the new fractions have equivalent values .

This is clearly explained with money.

A 1 Dollar bill is NOT the same as 4 QUARTER COINS or 10 DIMES or even 100 PENNIES. but they DO ALL HAVE THE SAME VALUE, or in math speak, they are equivalent to each other.

Now let's look at the following:

Taking a look back at our original fraction 1 and our new fraction 1.

If you like this apprach and think your student will benifit from it, please get your free printable Common Denominator table worksheet here.

Of course this may also be stating the obviouse, but remember, your kid only needs one table per problem, I just have a lot here as I went through the procedure step by step! So each printable sheet has three tables on it, so is good for three questions!

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