192.
The greatest common multiple of any set of integers is infinite.
GCM(18, 42) = 6
8
24
12
2.
The answer is 6
6=2*3 7=7 8=2*2*2 6 and 8 both have 2's, but 8 has more. Cross out the 2 from 6. 3*7*2*2*2 =168
LCM: 54 GCD: 6
The greatest common multiple is infinite.
The GCM is infinite.