# How Big Is This Folder? Recursion

Work out how big a folder is when it holds folders, which hold more folders, as deep as anyone made them: why one loop, a loop in a loop and a loop per level all come up short, and the idea that fixes them, recursion.

![Cheat sheet: How Big Is This Folder? Recursion](https://fsdtrainingmedia.blob.core.windows.net/public/images/2026/11/485b3d385c4343a1a4a2fb5aa327dd12.webp)

- Category: Data Structures
- Level: Apprentice
- Tags: Base Case, data structures, Recursion (data-structures), Recursive Case
- Updated: November 3, 2026

Source: https://www.ask-codey.com/cheat-sheets/ds-recursion-cheat-sheet