What is a lowest common multiple?

The lowest common multiple (LCM), also called the least common multiple, is the smallest number that is a multiple of every number in a set. You find it by listing multiples of each number and picking the first one they share. It is used to add fractions with different denominators.

Examples

• Multiples of 4: 4, 8, 12; multiples of 6: 6, 12; the LCM is 12.
• The LCM of 3 and 5 is 15.
• The LCM of 2 and 8 is 8.

Quick facts

• The LCM is used to find a common denominator when adding fractions.
• The LCM of two numbers is never smaller than the larger number.