You won't find common factors by using lists of multiples. The least common factor of any set of integers is 1, no matter what you use.
The lists of factors of 126 and multiples of 12 do not have any numbers in common.
Common factors result from comparing the lists of factors of at least two integers and selecting the ones that are on both lists.
12, 24, 36, 49, 60, 72, 84 28, 56, 84
The multiples of 75: 75, 150, 225, 300, 375, 450, 525, 600, 675, 750, 825, ... The multiples of 250: 250, 500, 750, 1000, ... The least common multiple is the number in both lists that is the least. For 75 and 250, the least common multiple is 750.
Not to overstate the obvious, but factor lists are lists of factors. Once you have found all the factors of a number, it is customary to list them from least to greatest.
You need at least two numbers to find a GCF, whether their lists are organized or not.
The term common in the question means a multiple that is shared by one or more numbers.Since 42 is a single number, it can have no common multiples.If you said, 42 and 2, then we could look at the multiples of 42 and the multiples of 2, make two lists, and see what is in common with those two lists.If you list the multiples of 42 alone, you have nothing to compare it with.
Common denominators. These are called "common multiples". For example, multiples of 4 are: 4,8,12,16,20,24 ... . Multiples of 6 are: 6,12,18,24,30,36 ... . The numbers on both lists are the common multiples and they include: 12,24,36, ... . Specifically, the smallest number in any such list of common multiples (12 in this example) is known as the Least (or Lowest) Common Multiple or LCM.
Greatest Common Multiple? Infinity. For example: Multiples of 6 are 6,12,18,24,30,36, ... Multiples of 18 are 18, 36, 54, 72, ... Since 18 is a multiple of 6, you will always be able to find another common multiple as you extend the lists out. Do you mean LCM (Least Common Multiple)? Take a look at the above list, it is 18 DO you mean GCF (Greatest Common Factor)? Since 6 divides 6 and 18, 6 is the GCF.
On the lists of multiples of 24 and 30, 120 is the first number to appear on both lists.24, 48, 72, 96, 120, 14430, 60, 90, 120, 150
List the multiples.27, 54, 81, 108, 13536, 72, 108, 144108 is the smallest number on both lists.
List the multiples.36, 72, 108, 14427, 54, 81, 108, 135108 is the smallest number on both lists: the LCM.