Greatest Common Factors
Sunday July 12, 2009
Factors are numbers that divide evenly into a number. For instance for the number 8: 1, 2, and 4 will divide evenly into 8 and therefore are factors of 8, the largest factor of 8 is 8. Common factors can be very useful when trying to find common denominators for fractions. The greatest common factor of two or more numbers is the largest number that can divide evenly into each of the numbers.
Now, you can save yourself the computational work in finding the greatest common factors for any 2 numbers by using the common factor calculator.
Comments
There are 5 methods to do GFC and LCM (I have a video clip on http://www.youtube.com to introduce them.) but one which method is faster and more practical? It is surprising that most teachers in North America do not understand this method. It is “upside-down division method”.
You link didn’t go to a math video. Are you taking about the division algorithm? That is generally the most efficient but a bit complicated for middle schoolers.
Sorry, I just looked up “upside down division” and really it is not any different than using an “factor tree”. In one you end up with the prime factorization on the side; in the other you end with the prime factorization at the ends of the “branches”.