63, 126, 189 and so on.
The common multiples of 9 and 21 are 63, 126, 189 and so on.
There are infinitely many multiples of 9 and 21 so it is impossible to list them. One of their multiples is 9*21 = 189.
Any pair of numbers has an infinite set of common multiples. The lowest common multiple of 9 and 21 is 63 and the others are multiples of this, e.g. 63, 126, 189, 252, 315, ...
9
63, 126, 189 and so on.
They are: 63, 126.
The LCM is 63
63.
The LCM is 63.
14 and 21
Just 63
63 and its multiples