# Pre-Algebra Practice Questions: Comparing Fractions Using Cross-Multiplication

Cross-multiplication is a handy tool for finding the common denominator for two fractions, which is important for many operations involving fractions. In the following practice questions, you are asked to cross-multiply to compare fractions to find out which is greater or less.

## Practice questions

**1.** Find the lesser fraction:

**2.** Among these three fractions, which is greatest:

## Answers and explanations

**1.** Of the two fractions,

Cross-multiply to compare the two fractions:

Because 35 is less than 36,

**2.** Of the three fractions,

Use cross-multiplication to compare the first two fractions.

Because 21 is greater than 20, this means that 1/10 is greater than 2/21, so you can rule out 2/21. Next, compare 1/10 and 3/29 by cross-multiplying.

Because 30 is greater than 29, 3/29 is greater than 1/10. Therefore, 3/29 is the greatest of the three fractions.