Let us think of education as the means of developing our greatest abilities, because in each of us there is a private hope and dream which, fulfilled, can be translated into benefit for everyone and greater strength for our nation. John F. Kennedy U.S. President

MANNING MATH HELP         how to have success in class        math links on the web           geometry topics        algebra topics        mixed topics         Welcome letter       Math 1     Math 1 adv      Math 2 adv     Algebra 1 Hon       Algebra  2 Hon         home

=      +      ÷      ±     ∆      ∞       ×       π      Σ f(x)       %      ≤        !        ≠         *

The greatest common factor of two or more numbers can be found in a couple of different ways.

One straight forward way is to list the factors and choose the largest common one.

24: 1, 2, 3, 4, 6, 8, 12, 24                                                                40: 1, 2, 5, 8, 10, 20, 40

30: 1, 2, 3, 5, 6, 10, 15, 30                                                              100: 1, 2, 4, 5, 10, 20, 25, 50, 100

the largest factor listed in both is 6                                                     the largest factor listed in both is 20  

 

Another method is to use prime factorization.  Identify each pair of common prime factors.

24 = 2 * 2 * 2 * 3                                                                           40 = 2 * 2 * 2 * 5

30 = 2 * 3 * 5                                                                                 100 = 2 * 2 * 5 * 5

the common prime factors are 2 and 3.                                            the common prime factors are 2, 2, and 5

Their product gives the GCF as 6.                                                   Their product gives the GCF as 2 * 2 * 5 = 20