What is the Least Common Denominator? Definition and Examples


The least common divisor (LCD) of two or more common fractions is the least common multiple of the denominators.

For example, the least common divisor of 1/2 and 1/3 is 6.

6 is indeed the smallest number that is a multiple of both 2 and 3.

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Math words beginning with the letter l

How do you find the least common denominator?

1. List the multiples of each denominator

2. The smallest common factor is the least common divisor

Example

What is the LCD of 2/3 and 4/5

The multiples of 3 are 3, 6, 9, 12, 15, 18, 21, ...

The multiples of 5 are 5, 10, 15, 20, 25, 30, ...

Since the smallest common factor is 15, the least common denominator is 15.

What is the difference between the least common multiple and the least common denominator?

The least common multiple refers to numbers while the least common divisor refers to fractions. 

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