The common multiples of 9 and 21 are 63, 126, 189 and so on.
63
Oh, dude, 9 and 21 both go into numbers that are multiples of both 9 and 21. So, like, they can go into numbers like 63, 126, 189, and so on. It's just basic math, nothing too mind-blowing.
Factors: 1 and 3 Multiples: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30 and so on.
The multiples of 6 is 6,12,18,24,30,36,42,48,54,60,66,72,78,84,90.................. The multiples of 9 is 9,18,27,36,45,54,63,72,81,90,99,108,117,126,135...............
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
126
63 and its multiples
63, 126, 189 and so on.
63, 126, 189 and so on.
Just 63
The LCM is 63.
They are: 63, 126.
The LCM is 63