What is the least common multiple of 3, 4, 6 and 15?
One way to do this is to list the multiples of each number until I find a common one. The multiples of 3 are 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, etc. The multiples of 4 are 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, etc. The multiples of 6 are 6, 12, 18, 24, 30, 36, 42, 48, 54, 60, etc. The multiples of 15 are 15, 30, 45, 60, etc. I can see that the first multiple that appears in all four lists is 60. Therefore, 60 is the least common multiple of 3, 4, 6 and 15. 