Arithmetic Grade Four

Lesson Seventy-two: Reducing Fractions

Often reducing fractions to their lowest form is fairly easy, but it takes some practice to get good at it. You get some more practice reducing fractions in this lesson. 

  Let's say we want to reduce:

        21
       ----
        35
Reducing fractions requires a couple of steps:
  1. Find the Greatest Common Factor of the numerator and the demoninator.
  2. Divide both the numerator and the demoninator by the GCF.
Here's an example:

   Fraction:  21/35.
   Factors:
     21: {1, 3, 7, 21}.
     35: {1, 5, 7, 35}.
   GCF:  7.
   Divide the numerator and the denominator:
      21/7 = 3.
      35/7 = 5.
   Answer:  3/5.
Let's review finding GCFs again.

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