The easiest way to probably do this is to go through the times table of seven in your head and find anything similar numbers in the 6's multiplication table.
6: 6,12,18,24,30,36,42,
7: 7,14,21,28,35,42
42 is the first number that comes in both of the tables. Therefore the least common multiple of seven and six is 42.
42
168
The LCM is: 54
The LCM is 630.
The LCM is: 210
One, you freakin' idiot.
420
LCM(6, 7, 9) = 126.
168 is the least common multiple of 56 and 84
12
30
12