21, 42, 63. 84
there are 21 multiples.
63
7, 14, 21, 28, 35, 42, 49
Multiples of 3 less than 20 are {3,6,9,12,15,18}.
3, 6, 9, 12, 15, 18, 21, 24, 27.
Just 72.
Just 63
It is: 99
there are 21 multiples.
There are none. The lowest multiple of 21 is 21.
21,42,63,84
21, 42, 63, 84.
21, 42, 63, 84.
21: 21, 42, 63, and 84!
63.
21,42,63,84
21, 42, 63, 84