It is not possible to give a sensible answer to these questions. The least common multiple (LCM) refers to a multiple that is COMMON to two or more numbers. You have only one number in each of the three questions!
The LCM of 8, 12 and 15 is 120.
The LCM is: 60
The Least Common Multiple (LCM) of 12, 15, and 28 is 420.
12
372
The LCM is: 120
The Least Common Multiple (LCM) of 12 and 17 is 204.
The LCM of 12 and 18 is 36
The LCM is 120.
The LCM is 840.
The LCM is 600.
The Least Common Multiple (LCM) of 6, 8, and 15 is 120.
The LCM is 840.