
How to Add and Subtract Fractions with Unlike Denominators
Adding and subtracting fractions is a common maths problem every student has to solve at some point in their lives. Fractions are an excellent way to represent numbers and can be applied in various contexts. When you multiply like fractions together, the result is always a fraction.
With denominators, fractions can be added and subtracted. The process of adding and subtracting is done by checking the denominator. This section will discuss adding and subtracting fractions with denominators, one of the students’ most common problems. In addition to solving this problem, we will also discuss how to add or subtract fractions with denominators.
Addition of Fraction
How Do You Add or Subtract Fractions?
Fraction addition and subtraction follow similar rules, with the denominators checked before the addition or subtraction begins. After we have checked the denominators, we can add or subtract the specified fractions.
The denominators are examined in the following manner:
Numerators are added or subtracted if the denominators of the fractions are the same.
If the denominators differ, we convert the fractions to like fractions so that the denominators match, and then we add or subtract as needed.
Example: $\dfrac{1}{7}+\dfrac{4}{7}=\dfrac{5}{7}$
$\dfrac{4}{5}-\dfrac{1}{5}=\dfrac{3}{5}$
Adding and Subtracting Fractions with Like Denominators
As we just need to work with the numerators, adding and subtracting fractions with like denominators is fairly simple. Here, we just need to add the numerator, while keeping the same denominator.
How Do You Add Fractions with the Same Denominators?
The following are steps to be taken care of while adding fractions with the same or like denominator:
Step 1: First, we must add the numerators of the given fraction.
Step 2: Since the denominator is the same. So we will keep it.
Step 3: Now, just add the numerator.
$\dfrac{\mathrm{a}}{\mathrm{b}}+\dfrac{\mathrm{c}}{\mathrm{b}}=\dfrac{\mathrm{a}+\mathrm{c}}{\mathrm{b}}$
Note: For Subtractions also, the method is the same.
In this case, we need to subtract $\dfrac{2}{5} - \dfrac{1}{5}$. Let us understand the procedure using the following steps.
Step 1: We will subtract the numerators of the given fractions. Here, the numerators are 2 and 1, so it will be 2 - 1 = 1
Step 2: Retain the same denominator. Here, the denominator is 5.
Step 3: Therefore, the difference of $\dfrac{2}{5} - \dfrac{1}{5}$
= $\dfrac{2 - 1}{5}$
= $\dfrac{1}{5}$
Adding and Subtracting Fractions with Like Denominators: Examples
Example: Add the fractions together.
$\dfrac{3}{7}+\dfrac{2}{7}$
Ans: Both of the fraction’s denominators are 7. These fractions are simple to add since they have the same denominator. To do so, simply add their numerators and retain their denominator, which is $7 .$
$\dfrac{3}{7}+\dfrac{2}{7} =\dfrac{3+2}{7}$
$=\dfrac{5}{7}$
Example: Add the fractions together.
$\dfrac{2}{11}+\dfrac{1}{11}+\dfrac{5}{11}$
Ans: Place the sum over the common denominator, 11, after adding the numerators.
$\dfrac{2}{11}+\dfrac{1}{11}+\dfrac{5}{11}=\dfrac{2+1+5}{11}=\dfrac{8}{11}$.
Example: Find the value of $\dfrac{4}{5}$ - $\dfrac{2}{5}$
Ans: Let's use a rectangle model to subtract the decimal fractions $\dfrac{4}{5}$ and $\dfrac{2}{5}$. This model indicates $\dfrac{4}{5}$ by darkening 4 of the 5 components. To simulate deleting $\dfrac{2}{5}$, we will further shade 2 portions from our shaded model.
Subtraction of Fraction
Worksheet for Adding and Subtracting Fractions with Like Denominators
Here is a worksheet related to adding and subtracting fractions with denominators, which will be very useful for the students.
Q1. $\dfrac{5}{11}+\dfrac{4}{11}=$
Ans: $\dfrac{9}{11}$
Q2. $\dfrac{12}{20}-\dfrac{5}{20}=$
Ans: $\dfrac{7}{20}$
Q3. $\dfrac{12}{15}+\dfrac{9}{15}=$
Ans: $\dfrac{21}{15}$
Q4. $\dfrac{7}{15}-\dfrac{6}{15}=$
Ans: $\dfrac{1}{15}$
Q5. $\dfrac{7}{5}-\dfrac{4}{5}=$
Ans: $\dfrac{3}{5}$
Summary
This article taught us how to easily add or subtract fractions. What we have to do is just keep the denominator the same and add or subtract the numerator as per the requirement and then just solve it. In this way, we can easily add or subtract the like fractions. We have also added some solved examples and practice problems on adding and subtracting, like fractions. Through this, we can have more clarity on the topic. We hope this article will help you in getting command over the topic.
FAQs on Adding and Subtracting Fractions Made Easy
1. What is adding and subtracting fractions?
Adding and subtracting fractions means combining or taking away parts of a whole by using a common denominator. When fractions have the same denominator, you simply add or subtract the numerators and keep the denominator the same. When denominators are different, you must first find a common denominator.
- Same denominator: 3/8 + 2/8 = 5/8
- Different denominators: 1/2 + 1/3 → common denominator = 6 → 3/6 + 2/6 = 5/6
2. How do you add fractions with the same denominator?
To add fractions with the same denominator, add the numerators and keep the denominator unchanged. This works because the parts are already divided into equal pieces.
- Step 1: Add the numerators.
- Step 2: Keep the same denominator.
- Step 3: Simplify if possible.
3. How do you subtract fractions with the same denominator?
To subtract fractions with the same denominator, subtract the numerators and keep the denominator the same. The denominator does not change because the parts remain equal in size.
- Step 1: Subtract the numerators.
- Step 2: Keep the denominator.
- Step 3: Simplify the result.
4. How do you add fractions with different denominators?
To add fractions with different denominators, first find a least common denominator (LCD), rewrite each fraction, then add the numerators. This ensures both fractions represent equal-sized parts.
- Step 1: Find the LCD.
- Step 2: Convert each fraction to an equivalent fraction.
- Step 3: Add the numerators.
- Step 4: Simplify.
5. How do you subtract fractions with different denominators?
To subtract fractions with different denominators, find a common denominator, rewrite the fractions, and then subtract the numerators. The key step is using equivalent fractions.
- Step 1: Find the LCD.
- Step 2: Rewrite both fractions.
- Step 3: Subtract numerators.
- Step 4: Simplify.
6. What is the least common denominator (LCD)?
The least common denominator (LCD) is the smallest common multiple of the denominators of two or more fractions. It is used to rewrite fractions so they have the same denominator before adding or subtracting.
- Find multiples of each denominator.
- Choose the smallest common multiple.
7. Do you add or subtract the denominators when adding fractions?
No, you do not add or subtract denominators when adding or subtracting fractions; you only work with the numerators after finding a common denominator. The denominator represents the size of equal parts and must stay consistent.
- Incorrect: 1/4 + 1/4 = 2/8 ✘
- Correct: 1/4 + 1/4 = 2/4 = 1/2 ✔
8. How do you simplify a fraction after adding or subtracting?
To simplify a fraction, divide both the numerator and denominator by their greatest common factor (GCF). This reduces the fraction to its lowest terms.
- Find the GCF of numerator and denominator.
- Divide both by the GCF.
9. Can you add mixed numbers the same way as fractions?
Yes, you can add mixed numbers by converting them to improper fractions or by adding whole numbers and fractions separately. Both methods give the same result.
- Example: 1 1/2 + 2 1/3
- Convert: 3/2 + 7/3 → LCD = 6 → 9/6 + 14/6 = 23/6 = 3 5/6
10. What are common mistakes when adding and subtracting fractions?
Common mistakes when adding and subtracting fractions include changing denominators incorrectly, forgetting to simplify, and making arithmetic errors with numerators. Avoiding these helps improve accuracy in fraction calculations.
- Adding denominators directly (wrong method).
- Not finding the least common denominator.
- Forgetting to reduce to lowest terms.
- Sign errors in subtraction.





















