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.
The common multiples of 6, 7, and 8 are numbers that are divisible by all three of these numbers. To find the common multiples, we first list the multiples of each number: 6 (6, 12, 18, 24, 30, ...), 7 (7, 14, 21, 28, 35, ...), and 8 (8, 16, 24, 32, 40, ...). The common multiples of 6, 7, and 8 are the numbers that appear in all three lists, such as 24 and 48.
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.
7, 14, 21
There are not just three common multiples, but infinitely many. They are 168 and it multiples, so 1680 and 16800.
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.
14, 28, 42
35, 70, 105
1,6,7 check
21
63
42, 84 and 126