12 and any of its multiples
30
105
21
21
12, 24, 36, 48
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.
All multiples of 12 are also multiples of 6 and they all can be written as the sum of nine numbers.