fractions

Method 1 of 4: Adding and Subtracting Fractions

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   Find the lowest common denominator (bottom number). For both adding and subtracting fractions, you'll start with the same process. Figure out the lowest common fraction that both denominators can go into.
   • For example, if you have 1/4 and 1/6, the lowest common denominator is 12. (4x3=12, 6x2=12)
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   Multiply fractions to match the lowest common denominator. Remember that when you're doing this, you're not actually changing the number, just the terms in which it's expressed. Think of it like a pizza - 1/2 of a pizza and 2/4 of a pizza are the same amount.
   • Figure out how many times your current denominator goes into the lowest common denominator. For 1/4, 4 multiplied by 3 is 12. For 1/6, 6 multiplied by 2 is 12.
   • Multiply the fraction's numerator and denominator by that number. For 1/4, you would multiply both 1 and 4 by 3, coming up with 3/12. 1/6 multiplied by 2 becomes 2/12. Now your problem looks like 3/12 + 2/12 or 3/12 - 2/12.

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   Add or subtract the two numerators (top number) but NOT the denominators.The reason is because you are trying to say how many of that type of fraction you have, total. If you added the denominators as well, you would be changing what type of fractions they are.
   • For 3/12 + 2/12, your final answer is 5/12. For 3/12 - 2/12, it's 1/12

Method 2 of 4: Converting Mixed Numbers into Improper Fractions

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   Convert mixed numbers into improper fractions. Improper fractions are those whose numerators are larger than their denominators. (For example, 17/5.) If you are multiplying and dividing, you must convert mixed numbers into improper fractions before you begin the rest of your calculations.
   • Say you have the mixed number 3 2/5 (three and two-fifths).
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   Take the whole (non-fraction) number and multiply it by the denominator. #*In our example, that means 3 x 5, which is 15.
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   Add that answer to the numerator.
   • For our example, we add 15 + 2 to get 17
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   Put that amount over the original denominator and you will have an improper fraction.
   • In our case, we get 17/5.

Method 3 of 4: Multiplying Fractions

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   Make sure you're working with two fractions. These instructions work only if you have two fractions. If you have any mixed numbers involved, convert them to improper fractions first..
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   Multiply numerator x numerator, then multiply denominator x denominator.
   • So say I had 1/2 x 3/4, I would multiply 1 x 3 and 2 x 4. The answer is 3/8.

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   Make sure you're working with two fractions. Again, this process will work ONLY if you have already converted any mixed numbers into improper fractions.
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   Flip the second fraction upside down.
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   Change the division sign into a multiplication sign.
   • If you started with 8/15 ÷ 3/4 then it would become 8/15 x 4/3
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   Multiply top x top and bottom x bottom.
• 8 x 4 is 32 and 15 x 3 is 45, so the final answer is 32/4

http://www.wikihow.com/Solve-Fraction-Questions-in-Math

Presentation arturo p. sanglay from arturosanglay