The LCM is 56.
14, 28, 42
8
The only common factor of four and seven is one, because seven is a prime number.
28, 56, 84 you can always find a common multiple of two numbers by multiplying them (but that won't always be the least common multiple)... the other common multiples can b found by multiplying that number with any other positive integer... for example, if you have two numbers (a and b), then one of their common multiples is a x b (but not always the smallest one), and the others are 2 x a x b, or any other positive integer times a x b
3 * 7
84
154 (there is only one least common multiple)
7 is a prime number. The answer is 1.
14, 28, 42
168
168.
8
280
Multiples of seven include 7, 14, 21, 28, 35, 42, 49 and so on. For them to be common, they need to be compared to another set of multiples.
Fourteenths (eight and seven)
The LCM of consecutive integers is their product. Consecutive integers will not both be multiples of seven.
Any multiple of 21.