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Welcome to my math blog! The purpose of this blog is to help you stay informed about our learning and experiences that have taken place during our math class. I have also included links your child (and you) may want to use in order to supplement math learning in 5th grade.

Wednesday, January 28, 2015

Adding and Subtracting Mixed Numbers

We put all of our fraction knowledge to work today.  In order to add and subtract mixed numbers, we had to do all of the following:

  • First, we had to convert our mixed numbers into improper fractions (p. 26 of our journal)

  • Once we had our improper fractions, we needed to determine a common denominator (p. 25 of our journal).  This includes:
    • making factor trees for our two denominators
    • creating a venn diagram to place our prime factors into
    • determine our common denominator by multiplying all of the numbers on the venn

  • Now that we have a common denominator, we have to make equivalent fractions with our improper fractions.
  • Next, we add or subtract.
  • Now take the answer, which is still an improper fraction, and  turn it back into a mixed number (p. 26 our our journal)

  • Now, we need to determine if it can be simplified (p. 25 of our journal).  This includes:
    • First, seeing if either the numerator or denominator is prime (p. 24 our our journal).  
      • If it is prime, then see if the other number is a multiple and divide by it.
      • If it isn't prime then we need to find our greatest common factor.
    • To find our greatest common factor:
      • make factor trees for our numerator and denominator
      • create a venn diagram to place our prime factors into
      • any numbers in the center section of the venn need to be multiplied together, this is the GCF

    • Once we have the GCF, the numerator AND denominator need to be divided by that number
We followed this procedure on our assignment, "A Magical Getaway."  I found this worksheet in The Mailbox Magazine, Dec/Jan, 2011 issue, p. 12.  To view the first four problems being solved, please watch:  Adding and Subtracting Mixed Numbers.

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