Least Common Denominator (LCD)

Definition of Least Common Denominator (LCD)

Least Common Denominator is the least common multiple of two or more of fractions.

More About Least Common Denominator (LCD)

    It is also called as Lowest Common Denominator.
    Steps to find the Least Common Denominator:
    1. First find the multiples of the denominators.
    2. Identify the least common multiple.

Video Examples: Least Common Denominator - Fractions Tip


Example of Least Common Denominator (LCD)

    To find the least common denominator of the fractions 4/7and 1/3, first we need to find the multiples of the denominator 7 i.e. 7, 14, 21, 28, 35 . . . and the multiples of the denominator 3 i.e. 3, 6, 9, 12, 15, 18, 21, 24 . . .
    The least common multiple of the denominators 7 and 3 is 21.
    So, the least common denominator of the fractionsand4/7 and1/3 is 21.

Solved Example on Least Common Denominator (LCD)

Ques: Find the least common denominator of the given expression. 5/4 + 7/12

    Choices:
    A. 12
    B. 16
    C. 4
    D. 21
    Correct Answer: A

Solution:

    Step 1: The denominators of the given fractions are 4 and 12.
    Step 2: Multiples of 4 are 4, 8, 12, 16, 20 . . .
    Step 3: Multiples of 12 are 12, 24, 36, 48 . . .
    Step 4: The lowest multiple the numbers have in common is 12.
    Step 5: So, the least common denominator of the given fractions is 12.