Any multiple of 126.
126, 252, 378
Any multiple of 126.
There are infinite amount of multiples of each. But a few are: 9: 9, 18, 27, 36, 45, 54, 63, 72, 80,... 42: 42, 84, 126, 168, 210, 252,... If you keep listing out the multiples of 9, you'll see the least common multiple of 9 and 42 is 126.
Each common multiple of 9 and 10 occurs exactly once (in the list of common multiples), so there is no common multiple that occurs the most. All common multiples of 9 and 10 are the multiples of their least common multiple which is 90.
18,36,54,72,90,
That's an infinite list: All multiples of 9.
The greatest common multiple is an infinite number, and not very practical for everyday use.
Multiples of 3 are 3, 6, 9 and so on. Multiples of 7 are 7, 14, 21 and so on. The common multiples of 3 and 7 include 21, 42, 63 and so on.
18 is a multiple of 9. To be an LCM, it has to be compared to another list of multiples.
They're all multiples of 3.
Common multiples of 9 and 10 are all of the multiples of 90.