I'm hardly "grilling" you, just trying to understand what you're actually trying to do so we can actually offer some help; you didn't clarify, your question is unclear so drop the 'tude

I suspect that you just want a text file, they can hold numbers and strings - as to how you store it, you're probably better off using an already established format as there will be libraries to make reading and writing easier. CSV and XML spring to mind as possible options. Excel files >2003 are XML files (if you want to have a look, change an excel file extension form .xlsx to .zip, open it up and have a dig).

CSV is theoretically simpler and a flat structure, but surprisingly tricky to write, Excel will export a sheet to csv though so this may be a good option - you can also use ADO to read them which can make things a breeze if you're thinking of putting in a lot of info.

There isn't really a one size fits all format, that's why there are so many different formats and extension, it really depends on what you want to do with these files after they've been made and how your data is structured, does that help any?