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    how to add fractions

    0  Views: 189 Answers: 2 Posted: 10 years ago

    2 Answers

    I just answered this the other day.  What's going on here??
    chelleanne is correct.   The denominator (bottom) numbers must be the same.   Picture a pizza cut into 6 pieces and another pizza cut into 8 pieces.  If you had 2 of one and 5 of the other, how much of a whole pizza would you have?

    2/6    +    5/8    =   N
    2/6 is the same as 1/3.........   1/3  +    5/8    =   N
    You need to find the "lowest common multiple"  for 3 and 8.  That is the smallest number that 3 and 8 are both factors.  That means 3 and 8 are numbers that can be multiplied with another number to reach the same product    A product is the answer in multiplication.  

    Using the larger denominator (8), start multiplying until you come to a product that also has 3 as a factor.   8 x 1 = 8  (nope)     8 x 2 = 16  (nope   3 x 5 is 15.   3 x 6 is 18)    8 x 3 = 24  (OK! That works for obvious reasons)

    NOW.....if we are changing the denominators to 24, we must make equal adjustments to the numerators......    You have to multiply 1/3  by 8    8/24.     You multiply 5/8 by 3     15/24

    NOW you can add the numerators.  As stated previously, the denominator is not added.
    8/24   +    15/24     =    23/24        And there's your answer.  To make your pizza look like this:
    take the pizza cut into 6 pieces and cut each remaining piece into 4 pieces.  You have two pieces left, each cut into 4 piece = 8 pieces.
    take the pizza cut into 8 slices and cut each of the remaining 5 pieces into 3.  You'll have 15 pieces.    15 pieces of 1 and 8 of the other is 23 of 24 total pieces that would equal 1 pizza.   

    The denominator MUST be the same number. You do not add the denominator. You ONLY add the NUMERATOR. 


    Ex.1    


     2/5 + 1/5 = 3/5


    7/8 + 3/4 = 


             3/4 * 2/2 = 6/8


    So, 7/8 + 6/8 = 13/8


    13/8 = 1 5/8


    Ex. 2


    2 3/4 + 3 1/3 =


       3/4*3/3 = 9/12


       1/3*4/4 = 4/12


    So, 2 9/12 + 3 4/12 = 5 13/12 


                                               13/12 = 1 1/12


    5 + 1 1/12 = 6 1/12


     



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