1. The problem asks us to identify which number is irrational. 2. An irrational number is a number that cannot be expressed as a fraction $\frac{a}{b}$ where $a$ and $b$ are integers and $b \neq 0$. 3. Common examples of irrational numbers include $\sqrt{2}$, $\pi$, and $e$. 4. To determine if a number is irrational, check if it can be simplified to a fraction or if it is a non-repeating, non-terminating decimal. 5. Without the list of numbers provided, we cannot specify which one is irrational. 6. Please provide the numbers to identify the irrational one.