While it’s not quite as easy as opening .docx files in Pages for Mac, it’s not an overly complicated process either. Here's how to open .xlsx spreadsheet files on Mac, iPhone or iPad.

By design, Apple uses its own Numbers (.numbers) file format, while Excel uses the XLSX file format, or for earlier spreadsheets, the XLS format. You can open XLSX files in Numbers, but you can ...

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.

In comparison, an XLSX file is a regular Excel spreadsheet that doesn't contain this type of code and doesn't require any special steps to open the file and start working.