1. The problem is to understand how to write a lower case lambda symbol with a lower number (subscript) under it. 2. In mathematics and physics, subscripts are used to denote specific elements or indices related to a variable or symbol. 3. The lambda symbol is written as $\lambda$ in LaTeX. 4. To add a subscript (a lower number) under the lambda symbol, use the underscore character followed by the subscript inside curly braces: $\lambda_{n}$ where $n$ is the subscript number. 5. For example, if the subscript number is 3, write it as $\lambda_{3}$. 6. This notation is common in sequences, eigenvalues, or other indexed variables. Final answer: $\lambda_{n}$ where $n$ is the lower number under the lambda symbol.