The only multiple of 21 and 9 that is less than 100 is 63
21,42,63,84
21, 42, 63, 84.
21: 21, 42, 63, and 84!
21,42,63,84
21, 42, 63, 84
21, 42, 63, 84.
63
Just 63.
63
Just 63.
They are: 21, 42, 63 and 84
99, but that's probably not what you want to know. There are 21 factors of 360 that are less than 100.