Last updated on July 4th, 2025
The number written below the fraction bar is the denominator; it represents the total number of parts of an object. In this topic, we will learn more about denominators, common denominators, operations on denominators, and examples.
A fraction has two parts: a numerator and a denominator. The denominator represents the total number of parts the object is divided into. The fraction is written in the form p/q, where p is the numerator and q is the denominator. The numerator and denominator are separated by the symbol “/”; this is known as the fraction bar. For example, 2/5, where 2 is the numerator and 5 is the denominator.
There are a few differences between the numerator and the denominator, in this section, let’s learn the key differences.
Numerator | Denominator |
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A proper fraction is a fraction where the numerator is always smaller than the denominator. Based on the denominators and the relationship between numerator and denominator, the fractions can be proper or improper fractions. Here are a few types of denominators.
Types of Denominators | Definition | Example |
Simple Denominator | When the denominator is only divisible by 1 and the number itself, then the denominator is a simple denominator. In other words, if the denominators are prime. | 5, 7, 11 |
Composite Denominator | In composite denominators, the denominators are always composite numbers, that is, they have factors other than 1 and the number itself. | 4, 8, 9 |
Like Denominator | A like denominator is when two or more fractions have the same denominator. | 5/2, 6/2, 7/2 |
Unlike Denominator | Unlike denominators are when two or more fractions have different denominators. | 5/2, 9/4, 6/5 |
Using fractions, we can perform basic operations like addition, subtraction, multiplication, and division. Let’s see how the operations on the denominator can be performed.
Addition and Subtraction in Fractions
In addition and subtraction in fractions, we first need to check the type of denominator, that is, whether it is like or unlike the denominator. If the fractions have like denominators, we first add or subtract the numerator and keep the denominator unchanged. But if the denominator is unlike, we need to find the LCD (least common denominator).
For example,
Multiplication and Division in Fractions
In multiplication, the numerators are multiplied together, and the denominators are multiplied together. In division, we multiply the first fraction by the reciprocal of the second fraction.
For example,
When the denominator has an irrational number that can be a square root or cube root, for example, 5/√2. The process of removing or simplifying the irrational number from the denominator is known as rationalizing the denominator. For rationalizing a denominator, the numerator and denominator are multiplied by the radical in the denominator.
For example, 5/√2 can be rationalized by multiplying the numerator and denominator with √2
That is 5/√2 × √2/√2 = 5√2/2.
In real life, the common denominator plays a major role, as it is used to compare, add, and subtract fractions. Let’s discuss a few real-life applications of the common denominator.
When working with fractions, students tend to make errors as they confuse the numerators, denominators, and operations. So, let’s discuss some common mistakes and the ways to avoid them.
Rationalize the denominator of 3/√5
The rational denominator equivalent for 3/√5 is 3√5/5.
To find the rational denominator of 3/√5 we multiply the fraction with √5/√5
That is 3/√5 × √5/√5 = 3√5/(√5 × √5)
= 3√5/5
Find the value of 2/5 + 6/5
The sum of 2/5 and 6/5 is 8/5.
Both fractions have a common denominator, that is 5.
So adding the numerators directly, 2/5 + 6/5
= (2 + 6) / 5
= 8/5
Find the value of 22/5 - 12/5
The difference between 22/5 and 12/5 is 2
The fractions, 22/5 and 12/5 shares a common denominator
So we subtract the numerators directly, that is
(22 - 12) / 5 = 10/5 = 2
Simplify the fraction 24/60
The fraction 24/60 can be simplified as 2/5
To simplify the fraction, we find the GCF of 24 and 60.
GCF of 24 and 60 is 12
So, dividing both the numerator and denominator by 12;
(24 ÷ 12) / (60 ÷ 12)
= 2/5.
Divide 5/6 ÷ 2/3
5/6 ÷ 2/3 = 5/4
To divide a fraction, we first find the reciprocal of the second fraction, that is ⅔ = 3/2
Now the first fraction is multiplied with the reciprocal of the second fraction
5/6 ÷ 2/3 = 5/6 × 3/2
= 15/12 = 5/4
Hiralee Lalitkumar Makwana has almost two years of teaching experience. She is a number ninja as she loves numbers. Her interest in numbers can be seen in the way she cracks math puzzles and hidden patterns.
: She loves to read number jokes and games.