venkyranjan2004-create/mern_labsheet ? reverse-engineered prompt

Build me a small JavaScript utility project for Node that groups together a few common helper functions for math, strings, arrays, and files.

I want each area to be separated into its own file, with a simple main entry file that pulls everything together so it’s easy to import and use. Make the helpers practical and easy to read, with a few sensible examples or simple usage tests so I can see that each one works. If there’s a better way to organize the code for a tiny utility package, go with that and keep it clean.

Please also make sure the project runs without extra hassle, and include whatever basic setup is needed so someone can open it and immediately understand how to use the functions. If you need to look up current docs online for anything, feel free to do that.