What is the Least Common Multiple (LCM) for 9 and 15?

To find the Least Common Multiple for the numbers 9 and 15 we need to first write the factors fore each number. The factors of 9 are: 9, 18, 27, 36, and 45. The factors of 15 are 15, 30, and 45. The number they have in common is 45, this is the LCM. The Least Common Multiple is the smallest common multiple that is divisible by 9 and 15. This is useful when adding, subtracting, or comparing simple fractions.