Apple's Numbers spreadsheet for Mac, iPhone, and iPad, is not as powerful as Microsoft Excel, but most users will be hard-pressed to find its limitations — and will immediately see how much easier ...

If Auto Save feature is not working in Excel, Word or PowerPoint, follow this guide that mentions different solutions to resolve the issue.

If you cannot open an Excel file and see Excel cannot open the file because the file format or extension is not valid error, see this post.