Office for Mac does not by default save files with file extensions.
In Word, PowerPoint, or Excel:
- Save your document (or if it is already saved, click Save As:). The Save window will appear. Name your document and click the down arrow.
At the lower left corner of the window is a Hide extension check box.
1. UNCHECK Hide extension.
2. MAKE SURE that the file extension appears. 3. Click Save.