How to Know When One Fraction Is Larger Than Another Fraction

You can tell which fraction is bigger by cross-multiplying.
••• Comstock Images/Comstock/Getty Images

When students take math exams, they need to know when one fraction is greater than another one. This is especially true in a subtraction problem when the smaller fraction needs to be subtracted from the larger fraction. Gauging fractions also comes in handy when several fractions must be placed from the least to the greatest or from the largest to the smallest.

    Choose a couple of fractions to work with. For example, consider 6/11 and 5/9. Take the denominator of the second fraction, 9, and multiply it by the numerator of the first fraction, 6. The product is 54. Write this number above the first fraction.

    Take the denominator of the first fraction, 11, and multiply it by the numerator of the second fraction, 5. The product is 55. Write that number above the second fraction.

    Compare the numbers you have written above the fractions. Because 55 is larger than 54, the second fraction, 5/9, is larger than the first fraction, 6/11.

    Apply this technique to any two fractions A/B and C/D, such that A, B, C and D are whole numbers, each greater than zero. If the product of A x D is greater than the product of C x B, the fraction A/B is larger than C/D. Similarly, if the product of A x D is less than the product of C x B, the fraction A/B is smaller than the fraction C/D.

    Tips

    • Another way to illustrate this is to find the common denominator of the two fractions. In the case of 6/11 and 5/9, the common denominator is 99 (9 x 11). Multiply the numerator and denominator of 6/11 by 9 to get 54/99, and multiply the numerator and denominator of 5/9 by 11 to get 55/99. This shows that 55/99, or 5/9, is greater than 54/99, or 6/11.

Related Articles

Adding & Subtracting Fractions
How to Cross Multiply
How to Convert a Fraction to a Ratio
How to Convert Mixed Numbers and Improper Fractions
How to Calculate the Percentage of Another Number
How to Divide Rational Numbers
How to Compare Negative Fractions
How to Find the Product of Fractions
How to Find Patterns in Fractions
Multiplying Fractions
How to Change Improper Fractions to Mixed Numbers or...
How to Find a Percent of a Fraction
How to Turn Fractions Into Integers
How to Divide a Fraction in Half
How to: Improper Fractions Into Proper Fractions
How to Calculate a Percentage and Solve Percent Problems
How to Find a Fraction of a Number
How to Do Fractions With a TI 83 Calculator
How to Divide Ratios
How to Arrange Fractions in Size Order

Dont Go!

We Have More Great Sciencing Articles!