How is common factors and greatest common factors similar and different?

Answer 1

They really aren't all that similar...

Greastest common factor finds the greatest number that you can divide both numbers by... for example, the GCF of 15 and 20 is 5, because 15 / 3 = 5 and 20 / 4 = 5, there is no higher number for division purposes that the two share. 10 is higher than 5 in the case of 20, but you cannot divide 15 by 10 without getting a remainder of 5.

Least common multiple finds the smallest common number that you can get when multiplying a number... for example, the LCM of 15 and 45 is 15 itself; 15 x 1 = 15, and 15 x 3 = 45. There is no smaller number that you can find that is common between the two. Another example, since the previous one had an LCM of an actual number being asked would be 18 and 24... in this case it would be 72 because there is no smaller number that the two share when multiplied by another value.

They are somewhat similar in how you find the end value, however. By dividing the two given numbers in the case of LCM, you will eventually break them up into prime numbers. Eliminating all similar numbers and then multiplying what is left will give you the LCM. In the case of GCF, by doing the same thing minus multiplying the prime numbers, you will end up finding the greatest number that the two are divisible by.

Answer 2

The greatest common factor, or GCF, is the largest positive integer that will divide evenly with no remainder into all the members of a given set of numbers. The least common multiple, or LCM, is the smallest positive integer that all the members of a given set of numbers will divide into evenly with no remainder. They are both common values of a given set of numbers.

Answer 3

A factor is a number by which another is exactly divisible. Every number has factors. Some numbers have the same factors as other numbers. Those are common factors. When comparing lists of common factors, the largest number is called the greatest common factor, or GCF.

Answer 4

The greatest common factor, or GCF, is the largest positive integer that will divide evenly with no remainder into all the members of a given set of numbers. The least common multiple, or LCM, is the smallest positive integer that all the members of a given set of numbers will divide into evenly with no remainder.