How do you figure out the highest common factor?

Answer by  MathTeacher (299)

To find the greatest common factor between two (or more) numbers, you must list all the factors of each number and then find the highest factor that they have in common.

Answer by  AWilliams (62)

First, list the prime factors of each number. Now, find the factors both numbers have in common and multiply them together. For example, the prime factors of 12 are 2, 2, and 3. The prime factors of 30 are 2, 3, and 5. There's one 2 and one 3 in common, so the greatest common factor is 6.

Answer by  exe (11)

You do the prime factorization of the numbers. You take out the common factors and then you multiply all the common factors and you get the highest common factor. It's somewhat similar to finding the Lowest common multiple but unlike LCM all you have to do is only take the common factors.

Answer by  blefuska (16)

you divide the given numbers by prime numbers (2,3,5,...) until your division result is 1, then you take all the common prime numbers you got with the minimum amount of each and multiply them(e.g. if you got 2,2,3 and 2,3 you take 2**=6)