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# Adding and Subtracing Fractions With Different Denomerators

## on Sep 26, 2007

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## Adding and Subtracing Fractions With Different DenomeratorsPresentation Transcript

• Adding and Subtracting Fractions With Different Denominators By: MP
• Adding Fractions With Different Denominators
• 2/3 + 3/4 = x Once you get your question, try to represent it in a way that it will be easier to understand or picture the question. Understanding the Problem
• Finding The Common Denominator To find the common denominator, make a list of all the factors in each denominator, until you find a factor that is common in each denominator (try to look for the least common denominator). 3: 3, 6, 9,12, 18, 21, 24 4: 4, 8, 12, 16, 24, 28, 32, 36 In this problem, the common denominator is 12.
• Representing The Common Denominator 4/12 + 9/12 = x Now that you have converted your question in a way that they have the same denominator, you can add.
• Adding The Question To add the question you add the numerator and leave the denominator. 8/12 + 9/12 = 17/12 Although, this question doesn’t look right it will make more sense if you make your sum into a mixed fraction. To make the sum into a mixed fraction, divide the numerator into the denominator.
• Making It Into A Mixed Number Since the sum is an improper fraction, you have to make it into a mixed number. A mixed number is a number with a whole number and, a fraction that is not improper. 17/12 as a mixed number is 1 5/12 You get this mixed number by dividing the denominator by the numerator, or subtracting the denominator by the numerator.
• Subtracting Fractions With Different Denominators
• Understanding the Problem 2/3 – 4/7=x Once you get your question, try to represent it in a way that you would understand it better (i.e. a table).
• Finding The Common Denominator
• To find the common denominator, make a list of all the factors in each denominator, until you find a factor that is common in each denominator (try to look for the least common denominator).
3: 3 6 9 12 15 18 21 7: 7 14 21 In this problem, the common denominator is 21.
• Representing The Common Denominator 14/21- 12/21=x Now that you have converted your question in a way that they have the same denominator, you can subtract.
• Subtracting The Problem To subtract your question, subtract the numerators and leave the denominators. 14/21- 12/21= 28/21 Although, this question doesn’t look right it will make more sense if you make your sum into a mixed fraction.
• Making It Into A Mixed Number
• Since the sum is an improper fraction, you have to make it into a mixed number.
• A mixed number is a number with a whole number and, a fraction that is not improper.
28/21 as a mixed number is 117/21 or 1 1/3 You get this mixed number by dividing the denominator by the numerator, or subtracting the denominator by the numerator.