How to Add and Subtract Fractions
Once you know the trick to adding and subtracting fractions with different denominators, you'll have no problem with these problems.
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You Will Need
- Two fractions
- A pencil and paper
Steps
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Step 1
Add fractions with same denominator
Add or subtract the numerators and keep the same denominator if the fractions have the same denominator.
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The numerator is the number on the top, and the denominator the number on the bottom of the fraction.
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Step 2
Find a common denominator
Find the lowest common denominator to both fractions if they have different denominators. For example, if you add 1/3 plus 3/8, the least common denominator is 24, since three times eight equals 24.
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The lowest common denominator is the smallest common multiple of both denominators.
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Step 3
Rewrite the fractions
Rewrite the fractions, using the lowest common denominator. Multiply the numerator by the same number by which you multiplied the denominator.
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Step 4
Add or subtract the numerators
Add or subtract the numerators and write the sum over the common denominator. The sum of 9/24 and 8/24 is 17/24. The difference is 1/24.
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Step 5
Reduce the fraction
If necessary, reduce the fraction by dividing the numerator and denominator by the highest number you can.
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A fraction in which the numerator is larger than the denominator is called an improper fraction.
