Rational numbers take the form \( \frac{p}{q} \), where both ‘p’ and ‘q’ can represent any integer, with the condition that \( q \neq 0 \). This definition encompasses a broad spectrum of numerical entities, ranging from natural numbers and whole numbers to integers, fractions of integers, and various forms of decimals, including both terminating and recurring decimals. In this lesson, we will delve deeper into the concept of rational numbers, exploring how to identify them and providing examples that illustrate their diverse nature.
Table of Contents
What are Rational Numbers?
The term “rational” is derived from “ratio,” emphasizing the fundamental characteristic of these numbers as representing a ratio of two integers. Rational numbers are contrasted with irrational numbers, which cannot be expressed as simple fractions and have nonrepeating, nonterminating decimal expansions.
Rational numbers are a category of numbers that can be expressed as the quotient or fraction \(\frac{p}{q}\), where both ‘p’ and ‘q’ are integers, and q is not equal to zero. This definition encompasses a wide range of numerical values, including integers, fractions, decimals (both terminating and recurring), and whole numbers. In essence, any number that can be expressed as a ratio of two integers falls under the umbrella of rational numbers.
Examples of Rational Numbers
 \(\frac{4}{3}\)
 \(\frac{5}{2}\)
 7 (can be expressed as\(\frac{7}{1}\), incorporating the idea of a ratio)
 0.60.6 (a terminating decimal)
 0.333…0.333… (a recurring decimal, expressed as \(\frac{1}{3}\)
Properties:
 Rational numbers can be positive or negative.
 They can be expressed as fractions, integers, or decimals (either terminating or recurring).
 The sum, difference, product, and quotient of two rational numbers are also rational.
How to Identify Rational Numbers?
Identifying rational numbers involves recognizing numerical values that can be expressed as fractions or ratios of integers. Here are key steps to identify rational numbers:
Fractional Form:
 Check for Fractions: Rational numbers are often presented in fractional form, \( \frac{p}{q}\)
, where ‘p’ and ‘q’ are integers and \(q \neq 0\). If a number is given in fraction format, it is a strong indicator that it is a rational number.
Decimal Representation:
 Terminating or Recurring Decimals: Rational numbers can also be represented as decimals. If the decimal representation of a number either terminates (ends) or repeats, it is a rational number. For example, 0.250.25 and 0.333…0.333… are rational.
Integer Form:
 Whole Numbers and Integers: Whole numbers and integers are considered rational numbers because they can be expressed as fractions. For instance, the integer 5 can be written as \(\frac{5}{1}\).
Excluded Cases:
 Avoid Irrational Numbers: Numbers that cannot be expressed as a simple fraction or have nonterminating, nonrepeating decimals are irrational. Examples include the square root of 2 \(\sqrt{2}\) or the mathematical constant π.
Applying the Definition:
Verify \(q \neq 0\): Ensure that the denominator (qq) in the fraction is not equal to zero, as division by zero is undefined. A rational number must have a nonzero denominator.
Rational and Irrational Numbers
Category  Rational Numbers  Irrational Numbers 

Definition  Expressed as \( \frac{p}{q} \), where \( p \) and \( q \) are integers, and \( q \neq 0 \)  Cannot be expressed as \( \frac{p}{q} \); nonrepeating, nonterminating decimals 
Examples 


Decimal Representation  Terminating or recurring decimals  Nonrepeating, nonterminating decimals 
Expression  Can be expressed as fractions, integers, or decimals  Cannot be expressed as a simple fraction 
Sum or Product  Sum or product of two rational numbers is rational  Sum or product involving an irrational number is irrational 