# factorial ## Find the factorial of a given number ```cpp int factorial(n); ``` will return the factorial of a given number. There is no custom return type, the function always returns an integer. ```cpp factorial(5); //120 factorial(0); //1 ``` {% hint style="warning" %} After n = 19, the function doesn't work anymore, as the numbers are too large for the integer sizing. Instead, use factorialL(n) for larger numbers. {% endhint %} --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://math-5.gitbook.io/math/reference/mathematical-operations/factorial.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.