12 is a multiple of 6, so any multiple of 12 will be a multiple of 6.

8 = 2^3

12 = (2^2)*3

The number must have factors of 2^3 and 3. 8*3 = 24. The smallest 3-digit multiple of 24 is

120/8 = 15

120/12 = 10

8 = 2^3

12 = (2^2)*3

The number must have factors of 2^3 and 3. 8*3 = 24. The smallest 3-digit multiple of 24 is

##### 5*24 = 120

120/6 = 20120/8 = 15

120/12 = 10