The common multiples of 3 and 21 are 21, 42, 63 and so on.
12 and any of its multiples
30
105
21
21
12, 24, 36, 48
All multiples of 12 are also multiples of 6 and they all can be written as the sum of nine numbers.
Multiples 21: 1,3,7,21Multiples 49: 1,7,49
LCM of 21 & 49 is 147, so all multiples of 147 are common multiples of 21 & 49.
The factors of 2 are 1 and 2. The factors of 3 are 1 and 3. Common multiples of 12 and 18 include any multiple of 36.
The first five multiples of 21 are: 21, 42, 63, 84, 105.
The first 5 multiples of 21 are: 21, 42, 63, 84, and 105.