M06, 106

Arithmetic Grade Six

Lesson One Hundred-six: Subtracting Fractions

Subtracting Fractions With UNLIKE Denominators

Find the lowest common denominator
Convert the fractions to have common denominators
Numerator: Just subtract the top numbers.
Denominator: Leave the bottom numbers alone.
Reduce if necessary

Here's an example:


  PROBLEM:  
             5         1     
            ---   -   ---  =
             6         3

  STEP ONE: Find LCD.

            The LCD of 6 and 3 is 6.

  STEP TWO: Convert fractions

            5        1 x 2
           ---  -   -------  =
            6        3 x 2

   THINK:

           5                1       ?
          ---              ---  =  ----
           6                3       6

   THEN JUST SUBTRACT THEM LIKE USUAL (and reduce if necessary).

Now you get to try a few for yourself.

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