With Unlike Denominators Adding & Subtracting Fractions With Unlike Denominators

Adding Fractions with Like Denominators 1 + 1 2 2 1 2 = Adding Fractions with UNLIKE Denominators 3 + 1 4 6 =

How do you find Common Denominators? The least common denominator, or LCD, of two fractions is the smallest number that can be divided by both denominators 3 + 1 4 6

Methods to Find the LCD Begin listing the multiples of both denominators until you can find a common one. 4x1 4x2 4x3 4x4 Multiples of 4: 4, 8, , 16 ____________________________ Multiples of 6: 6, , 18 12 6x1 6x2 6x3 12

Find the Greatest Common Factor of the denominators Finding the LCD Find the Greatest Common Factor of the denominators Multiply the Denominators together Divide the product of the denominators by the Greatest Common Factor.

What times the denominator equals the new number? 3 1 4 6 + 12 12 3 2

Creating the New Fractions 3 4 9 12 Multiply product by the original numerator Divide denominators + 2 12 1 6 Multiply product by the original numerator Divide denominators ________ ________

Add the Two Like Fractions 11 12 9 12 2 12 = +

Check out these sites to get some more practice Hyperlinks Check out these sites to get some more practice Addition-Unlike Denominators Least Common Multiple coolmath4kids

Courtesy of www.lessonplanspage.com Try it out with a Game! Fraction Matchin' Everyone has a note card. Some of you have problems with unlike denominators Others have the corresponding common denominator Find your match and work out the problem! card 1 matches card 2  1   2  +          1   4          4  +               4  Courtesy of www.lessonplanspage.com

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