Arithmetic/More About Multiplication/The Greatest Common Factor

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The Greatest common Factor (GCF) of two whole numbers is the highest number that can be divided by both of the original numbers to get a whole number result.

Finding the GCF of a number[edit]

  1. Write down to prime factorization of the two numbers.
  2. Find prime factors that are the same.
  3. Multiply the same prime factors together for the GCF.


  1. Notice that two and seven are used in both the equations?

  2. Therefore, the GCF of 28 and 98 is 14.