In mathematics, the lowest common denominator or least common denominator (abbreviated LCD) is the lowest common multiple of the denominators of a set of fractions. It simplifies adding, subtracting, and comparing fractions.
The lowest common denominator of a set of fractions is the lowest number that is a multiple of all the denominators: their lowest common multiple.
The product of the denominators is always a common denominator, as in:
but it is not always the lowest common denominator, as ...
