112, 224, 336
The common multiples of 7 and 16 are 112, 224, 336, 448, 560, 772, 884, 996, 1108, 1120, and so on. The LCM of 7 and 16 is 112, and so their common multiples are the infinite set of multiples of 112.
lcm(2, 7) = 14 → first 3 common multiples are: 14, 28, 42; lcm(2, 8) = 8 → first 3 common multiples are: 8, 16, 24; lcm(7, 8) = 56 → first 3 common multiples are: 56, 112, 168; lcm(2, 7, 8) = 56 → first 3 common multiples are: 56, 112, 168.
There are not just three common multiples, but infinitely many. They are 168 and it multiples, so 1680 and 16800.
7, 14, 21
If that's 1, 6 and 7, the answer is 42, 84 and 126. If that's 16 and 7, the answer is 112, 224 and 336.
1,6,7 check
14, 28, 42
35, 70, 105
21
63
14, 28, and 42
35, 70, 105