Which of the following numbers is NOT a rational number?

Step-by-step solution

1. A rational number can be expressed as a fraction $\frac{p}{q}$ where $p$ and $q$ are integers and $q\ne 0$.
2. $\frac{7}{9}$ fits this form – it is rational.
3. $-\frac{5}{2}$ also fits this form – it is rational.
4. $0.25$ can be written as $\frac{1}{4}$ – it is rational.
5. $\sqrt{2}$ cannot be expressed as a fraction of integers – it is irrational.

Concept tested: Rational vs Irrational numbers

Published 1 October 2026 · How this solution was prepared and checked