If you launch multiple files by double-clicking their shortcut icons, or via the "Open" menu in Excel, the files will run simultaneously in one Excel window.

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.

The format painter in Microsoft Excel already saves me so much time, and it's even more helpful when I double-click the button. The effect is especially helpful when I'm working on my family ...