A common multiple of the denominators of two or more fractions is called a Common Denominator.

More About Common Denominator

The least common multiple of the denominators of a set of fractions is called the lowest common denominator.

Video Examples:Math Antics - Common Denominator ECD

Example of Common Denominator

Common Denominator of 3/4 and 5/7 is 28 as:
Multiples of 4 are 4, 8, 12, 16, 20, 24, 28, 32,...
Multiples of 7 are 7, 14, 21, 28, 35,...
The common multiple of 4 and 7 is 28.

Solved Example onCommon Denominator

Ques: Identify the common denominator of two fractions 1/4 and 2/9 .

Choices:

A. 9
B. 4
C. 36
D. 13
Correct Answer: C

Solution:

Step 1: A common multiple of the denominators of two or more fractions is called a Common Denominator.
Step 2: Denominator of 1/4 is 4 and that of2/9 is 9.
Step 3: Multiples of 4 are: 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 40, 64, 68, 72,...
Multiples of 9: 9, 18, 27, 36, 45, 54, 63, 72, 81,...
Step 4: The common multiple of 4 and 9 is 36, 72,...
Step 5: So, the common denominator for1/4 and2/9 is 36.