The Least Common Denominator (LCD) is the smallest common denominator of two or more fractions.
Example: the LCD for 3/5, 1/6 and 1/15 is 30.
List the multiples of each denominator 5, 6 and 15
Multiples of 5 are 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60�..
Multiples of 6 are 12, 18, 24, 30, 36, 42, 48, 54, 60 ...
Multiples of 15 are 30, 45, 60�
30 is the smallest number that appears in each list.
Therefore, the least common denominator of 3/5, 1/6 and 1/15 is 30.