Adding Fractions with Different Denominators
Wednesday, June 30, 2010
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Addition Fractions - Unlike Denominators
How to Add Fractions with different denominators:
- Find the Least Common Denominator (LCD) of the fractions
- Rename the fractions to have the LCD
- Add the numerators of the fractions
- Simplify the Fraction
Example: Find the Sum of 2/9 and 3/12:
- Determine the Greatest Common Factor of 9 and 12 which is 3
- Either multiply the denominators and divide by the GCF (9*12=108, 108/3=36)
- OR - Divide one of the denominators by the GCF and multiply the answer by the other denominator (9/3=3, 3*12=36)
- Rename the fractions to use the Least Common Denominator(2/9=8/36, 3/12=9/36)
- The result is 8/36 + 9/36
- Add the numerators and put the sum over the LCD = 17/36
- Simplify the fraction if possible. In this case it is not possible
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