Adding and Subtracting Fractions

Fractions can be a nightmare for kids. Adding and subtracting can be more than that. So, this video is designed keeping in mind the trouble and confusion students often come across while dealing with fractions. The video explains clearly how to add and subtract fractions having same denominators with the help of few daily life examples making it more easier for the student(s) to relate and learn.

For more help, check out our Add and Subtract Fractions Lessons Page

Credit goes to Mr. J

Steps to Add and Subtract Fractions


How Do You Add Like Fractions?

Like fractions are fractions with the same denominator, which means they represent parts of a whole that have been divided into the same number of equal parts. Here are the steps to add like fractions:

Step 1) Add the Numerators

Once you have the same denominator for both fractions, simply add the numerators together. The denominator remains the same.

Step 2) Simplify (if necessary).

If the numerator is larger than the denominator after adding, you may need to simplify the fraction by dividing both the numerator and the denominator by their greatest common divisor (GCD) to get the simplest form.

Here’s an example:

Let’s add the fractions 2/5 and 3/5.

Step 1: Check that the denominators are the same. In this case, they are already the same, both being 5.

Step 2: Add the numerators. 2 + 3 = 5.

Step 3: Simplify (if necessary). In this case, 5/5 is already in its simplest form because the numerator and denominator have no common factors other than 1.

So, 2/5 + 3/5 = 5/5, which simplifies to 1.

The result is 1, which means that when you add 2/5 and 3/5 together, you get a whole, represented as 1 when simplified.


How Do You Add Unlike Fractions?

Adding unlike fractions involves fractions with different denominators. To add them together, you’ll need to find a common denominator and then perform the addition. Here are the steps for adding unlike fractions:

Step 1: Find a common denominator.

Look for the least common multiple (LCM) of the denominators. The LCM is the smallest number that both denominators can divide evenly into.

Step 2: Create equivalent fractions.

For each fraction, rewrite it as an equivalent fraction with the common denominator found in step 1. To do this, multiply both the numerator and denominator of each fraction by the same number that makes the denominator equal to the common denominator.

Step 3: Add the fractions.

Now that you have both fractions with the same denominator, add the numerators together while keeping the common denominator unchanged.

Step 4: Simplify (if necessary).

After adding the fractions, simplify the result by reducing it to its simplest form. This involves finding the greatest common divisor (GCD) of the numerator and denominator and dividing both by it.

Let’s illustrate these steps with an example:

Add the fractions 1/4 and 3/8.

Step 1: Find a common denominator.

The LCM of 4 and 8 is 8.

Step 2: Create equivalent fractions.

Rewrite 1/4 as an equivalent fraction with a denominator of 8 by multiplying both the numerator and denominator by 2. You get 2/8.
Since 3/8 already has an 8 as the denominator, you don’t need to change it.

Step 3: Add the fractions.

Now that both fractions have the same denominator (8), you can add the numerators: 2/8 + 3/8 = 5/8.

Step 4: Simplify (if necessary).

To simplify 5/8, find the GCD of 5 and 8, which is 1. Divide both the numerator and denominator by 1 to get the simplest form: 5/8.
So, 1/4 + 3/8 = 5/8 when simplified.


How Do You Subtract Like Fractions?

Subtracting like fractions is a straightforward process because like fractions have the same denominators. Here are the steps for subtracting like fractions:

Step 1: Subtract the numerators.

Once you have the same denominator for both fractions, simply subtract the numerator of the second fraction from the numerator of the first fraction. The denominator remains the same.

Step 2: Simplify (if necessary).

If the result is not already in its simplest form, simplify the fraction by finding the greatest common divisor (GCD) of the numerator and denominator and dividing both by it.
Here’s an example:

Let’s subtract the fractions 3/6 and 1/6.

Step 1: Check that the denominators are the same. In this case, both fractions already have the same denominator of 6.

Step 2: Subtract the numerators. 3 – 1 = 2.

Step 3: Simplify (if necessary). In this case, the result, 2/6, is not in its simplest form. To simplify, find the GCD of 2 and 6, which is 2, and divide both the numerator and denominator by 2.

2/6 simplifies to 1/3.

So, 3/6 – 1/6 = 1/3 when simplified.


How Do You Subtract Unlike Fractions?

Subtracting unlike fractions involves fractions with different denominators. To subtract them, you’ll need to find a common denominator and then perform the subtraction. Here are the steps for subtracting unlike fractions:

Step 1: Find a common denominator.

Determine the least common multiple (LCM) of the denominators. The LCM is the smallest number that both denominators can divide evenly into.

Step 2: Create equivalent fractions.

For each fraction, rewrite it as an equivalent fraction with the common denominator found in step 1. To do this, multiply both the numerator and denominator of each fraction by the same number that makes the denominator equal to the common denominator.

Step 3: Subtract the fractions.

Now that you have both fractions with the same denominator, subtract the numerators of the second fraction from the numerators of the first fraction while keeping the common denominator unchanged.

Step 4: Simplify (if necessary).

After subtracting the fractions, simplify the result by reducing it to its simplest form. This involves finding the greatest common divisor (GCD) of the numerator and denominator and dividing both by it.

Let’s illustrate these steps with an example:

Subtract the fractions 5/12 and 3/8.

Step 1: Find a common denominator.

The LCM of 12 and 8 is 24.

Step 2: Create equivalent fractions.

Rewrite 5/12 as an equivalent fraction with a denominator of 24 by multiplying both the numerator and denominator by 2. You get 10/24.
Rewrite 3/8 as an equivalent fraction with a denominator of 24 by multiplying both the numerator and denominator by 3. You get 9/24.

Step 3: Subtract the fractions.

Now that both fractions have the same denominator (24), you can subtract the numerators: 10/24 – 9/24 = 1/24.

Step 4: Simplify (if necessary).

The result, 1/24, is already in its simplest form because the numerator and denominator have no common factors other than 1.
So, 5/12 – 3/8 = 1/24 when simplified.