If a number is a multiple of 3, it is not necessary to a multiple of 12.
Explanation:
The numbers which are multipe of 3:
3, 6, 9, 12, 15, 18, 21, 24, ......
The numbers which are multipe of 12:
12, 24, 36, 48, ......
The number is multiple of 12 is also multiple of 3 but the number is multiple of 3 the number may be multiple of 12 or may not be multople of 12.
Thus, If a number is a multiple of 3, it is not necessary to a multiple of 12.