List all the multiples of 4 between 55 and 101
56, 60, 64, 68, 72, 76, 80, 84, 88, 92, 96, 100
List all the multiples of 9 between 55 and 101
63, 72, 81, 90, 99
List all the multiples of 12 between 55 and 101
60, 72, 84, 96
From the above 3 lists, choose all the common
72
The answer is 72
