LCM stands for least common multiple. We are being asked to find the lowest multiple that 6 and 15 have in common.
Multiples of a number (n) are integers that are the product of n and another number. Let's list the multiples of both 6 and 15:
6: 6, 12, 18, 24, 30, 36
15: 15, 30, 45, 60, 75, 90
The LCM of 6 and 15 is 30.