Least Common Denominator Calculator (LCD)

Stuck on tricky fraction problems? Our Least Common Denominator Calculator solves the struggle! Quickly find the LCD for any set of fractions to simplify adding, subtracting, or comparing them.

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Least Common Denominator Calculator (LCD)

About Least Common Denominator (LCD) Calculations

Definition: The LCD is the smallest number that is a common multiple of the denominators of two or more fractions. It is identical to the Least Common Multiple (LCM) of the denominators.

Even if you've never heard of a least common denominator (LCD) before, you've undoubtedly tried to find it. If not consciously, you've done so by being clever about the number you used to factor out as you combined graphs. After all, combining graphs was always a problem if the denominators weren't the same. Well, why did those common denominators always come to be? The answer is elementary! So what is this thing, commonly known as "least common denominator"? How is it found? I hope to show you that it's both valuable and pretty simple. Notice, please, that I said "simple", not "easy"! It is easy enough, but requires technique.

I'm a mathematician, so we'll use some math language here. That means we'll be brief, use some algebra ideas, and offer real solutions. I don't mean to "beef up" the subject matter, only tell you basic things. Still, if you're averse to algebra or to following sometimes cryptic but densely packed power lines of argument, you are going to have to adapt some of the details to your study routine. Just brush up on those algebra skills, okay? We are going to discover enough in the operation of the least common denominator to make studying LCD seem worthwhile. If you believe in that, even a little, you are likely to be thereby inspired to explore the area further. And a bit of thorough digging in your newfound gem mine could harbor extraordinary results, possibly setting off a chain of discoveries of epic proportions.

Formulas to Find LCD

Prime Factorization Method
Factor each denominator into prime numbers.
Multiply the highest power of every prime present.
Formula: LCD = ∏ (Highest powers of all primes)

2. GCD Method (for 2 denominators)
Use the Greatest Common Divisor (GCD):
Formula:

LCD (a,b) =
|a × b|
GCD (a,b)

3. Listing Multiples Method
List multiples of each denominator.
Identify the smallest common multiple.

Least Common Denominator calculation example (LCD)

We have given the calculation formula for the Least Common Denominator Calculation in the picture above.
We will use the steps below to calculate the least common multiple (LCD) for two or more fractions.
We will identify the denominators and find the prime factorization of each denominator. Later, we will factor each denominator into its prime factors.
We will identify the unique prime factors and list all the unique prime factors from the factors.
We will find the product of the unique prime factors and multiply all the unique prime factors obtained in step 3 together.

Example 1:

LCD of   
1
4
  and  
1
6

Denominators: 4, 6
Prime Factors:
4 = 22
6 = 2 × 3
Highest Powers: 22 × 3 = 12
LCD = 12

→ Rewrite fractions:   
1
4
  =   
13
12
  ,  
1
6
  =  
2
12

Example 2:

LCD of   
2
9
  ,  
5
12
  ,  
1
15

Denominators: 9, 12, 15
Prime Factors:
9 = 32
12 = 22 × 3
15 = 3 × 5
Highest Powers:  22 × 32 × 5 = 180
LCD = 180

→ Rewrite:   
2
9
  =  
40
180
  ,  
5
12
  =  
75
180
  ,  
1
15
  =  
12
180

Example 3:

LCD of   
3
8
  and  
5
14
  (GCD Method)

Denominators: 8, 14
GCD (8, 14) = 2

LCD =   
8 × 14
2
  =  
112
2
  = 56
→ Rewrite:   
3
8
  =  
21
56
  ,  
5
14
  =  
20
56

What is the Least Common Denominator Calculator

The Least Common Denominator calculator is a simple tool for finding the Least Common Denominator. It also needs you to enter the fraction number. It rolls out the Least Common Denominator, allowing for easier least common denominator calculation.

Simplifying Least Common Denominator calculations is the primary goal of the Least Common Denominator Calculator. You may work as an engineer, businessperson, student, or whatever, but calculating the Least Common Denominator is useful. This is how you save time and pick out great solutions.