Comparing Fractions

By: Greg StarkEC&I 831

Why compare fractions?

• To determine which fraction represents a larger value

Fractions with the same denominator are called like fractions and can be compared by their numerators

The larger fraction has the biggest numerator

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5

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What if the they are unlike fractions?

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3

5

It can be difficult to determine which fraction is larger by looking at a diagram

What if they are unlike fractions?• To determine which fraction represents a larger value with unlike

fractions:

1. Multiply each denominator by the opposite numerator

Important: always cross multiply from denominator (bottom) to opposing numerator (top) or this method will not work

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2. Write the product (answer) beside the numerator

3. The side with the largest product, is the larger fraction

7 X 3 = 215 X 4 = 20

What if there are more than two fractions?

• This method will still work

• You must compare each fraction to the others to ensure you have them in the correct order – a time consuming process

• Converting all of the fractions to like terms is another method which may make this easier

• This method is discussed in the Adding Unlike Fractions presentation

Review: to compare fractions

1. For like fractions, the larger fraction is the one with the larger numerator

2. For unlike fractions, multiply opposing denominators (bottom) to numerators (top)

– The side with the largest product is the larger fraction