This month's monster security patch for Office breaks Excel when it tries to open HTML files, and it seems unlikely Microsoft will fix the problem Excel users are reporting an odd bug in the way ...

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.

On the right side, select the Open checkboxes for the file types that you want to open in the Protected View. Now, select the Open selected file types in Protected View radio button at the bottom.

You can also have Excel open automatically. Disable Start screen and automatically open a blank Excel workbook By default, a Start screen appears when you open Excel (see the screenshot below). The ...

How to Open an XLS File in Excel. XLS files are Excel workbook files created in Excel 97 or Excel 2003. The 2007, 2010 and 2013 versions of the program use the XLSX format by default to save ...

How to Open Excel 2007 Files As Separate Windows. If you work with multiple Excel files over the course of a workday, and especially if you use a dual-monitor setup, you might wonder how you can ...

Numbers has the ability to open Excel files so you can work on them. You can also export spreadsheets in Numbers so that they are compatible with Excel.