This article explains two ways to add a degree symbol to PowerPoint slides. Instructions apply to PowerPoint 2019, 2016, 2013, 2010, and 2007.

PowerPoint probably won't give you confirmation that you've completed step 6. If, after clicking Insert, you want to check that the degree sign was actually inserted, simply move the dialog box to a different location or close it to check.

Keyboard shortcuts are more efficient, especially when inserting symbols like this. Otherwise, you would have to scroll through a list of dozens of other symbols to find the right one.

This method actually works anytime, wherever you are: in an email, web browser, etc.