Multiple of the denominators of two or more fractions.
The lowest common denominator for two or more fractions (LCM) is the lowest whole number that is also a multiple of each denominator in these fractions.
Example
- Consider the fractions \(\frac{4}{12}\) and \(\frac{8}{18}\) : the numbers 36 and 72 could act as a common denominator, but the lowest option is 36, which we call the Lowest Common Multiple of 12 and 18 and that we write as: LCM (12, 18) = 36.
- The common denominator of the fractions \(\frac{3}{10}\), \(\frac{7}{15}\) and \(\frac{11}{20}\) is 60.
Therefore, we write: LCM (10, 15, 20) = 60.