Math K-Plus

How To Compare Fractions Using Cross-Multiply

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What Is The Best Method To Compare Fractions

If your are Comparing Fractions with the same denominator, the Fraction with the largest numerator is the Fraction of greatest value; for example 3/8 is smaller in value than 7/8; think of a pizza, the first pizza has 3 slices but the second pizza has 7 slices. Seven slices of pizza is more than 3 slices.

When the denominators of two fractions are different, determining the larger value Fraction is not as simple. Before we investigate how to solve this type of problem, there is a rule that is important to understand. Rule: multiplying or dividing the numerator AND denominator of a fraction by the same number does not change the value of the fraction. We will show in the following example that 1/2 = 2/4.

12  =  1 × 22 × 2  =  24

When comparing fractions to determine if they are equal or Equivalent Fractions, follow these simple steps:
  • First Cross Multiply: (1) multiply the numerator of fraction one by the denominator of fraction two. (2) multiply the denominator of fraction one by the numerator of fraction two. If the two products from the multiplication are equal, the two fractions are Equivalent Fractions. Here is an example.

    Fraction One:  1821

    Fraction Two:  3035

    Cross Multiply Fractions

    One and Two

    18 x 35 = 630

    21 x 30 = 630

    We got the same product

    (630) from both fractions.

    These fractions are equivalent.

  • If the product resulting from the cross-multiply are not the same for both fractions, the fractions are not Equivalent Fractions. Then the larger fraction is the one with the largest numerator - denominator product. Example:

    37  >  25

    3 × 5 = 15

    7 × 2 = 14

    Fraction 3/7 is greater

    in value than fraction 2/5.

Please Read! These are instructions to input fractions into the calculator to compare their values: An fraction can be typed in this formatted. Example: 5/10, 26/30, etc.

Comparing Fractions Calculator
Enter Fraction To Compare Here
Then Press The SUBMIT Button