What are 6 least common multiples for 3, 4 and 6?

6 itself is a multiple of 3, so any multiple of 6 is also a multiple of 3.  We can
ignore the 3, and just find a number that's a common multiple of 4 and 6.

The way I do that is to investigate the multiples of 6, and just keep going until
I find one that's also a multiple of 4.

-- First multiple of 6 . . . 6.  No, that's not a multiple of 4.
-- Second multiple of 6 . . . 12. Yes !  That's a multiple of 4.

So the least common multiple of 3,4,and 6 is 12.
After that, of course, multiples of 12 are also multiples of  3,  4, and  6, as well as
multiples of other numbers.

The 6 smallest multiples of 3,4, and 6 are ...
 
12,  24,  36,  48,  60, and  72 .

3cm and 6 and 9 cm that a possibility of that question