California Assessment of Student Performance and Progress (CAASPP) Math Practice Exam

Which of the following best describes a rational number?

1. A number that is a perfect square

2. A number that can be written as a fraction

3. A number that has an infinite decimal expansion

4. A number that cannot be expressed in any form

The correct answer is: A number that can be written as a fraction

A rational number is defined as any number that can be expressed as the quotient or fraction of two integers, where the denominator is not zero. This means that for a number to be rational, it must be able to be written in the form of a fraction \( \frac{a}{b} \), where \( a \) and \( b \) are integers and \( b \) is not zero. The correct choice highlights this key characteristic. Rational numbers can include integers, finite decimals, and repeating decimals, as these can all be represented in fraction form. For example, the integer 5 can be expressed as \( \frac{5}{1} \), and the decimal 0.75 can be expressed as \( \frac{3}{4} \). The other options describe characteristics that do not accurately define rational numbers. For instance, perfect squares (like 1, 4, 9) are indeed rational numbers, but not all rational numbers are perfect squares. Infinite decimal expansions can be either rational (like 0.333...) or irrational (like 0.14159...), so the infinite decimal characteristic is not exclusive to rational numbers. Lastly, a number that cannot be expressed in any form is not rational at