You can add page numbers to your PowerPoint slideshow through the "Slide Master" page, which lets you edit your entire slideshow at once.

How to Change Page Numbers on a PowerPoint 2007 Handout. Microsoft PowerPoint 2007 handouts are an ideal way to keep your message in front of your audience after broadcasting a presentation on the ...

In PowerPoint 2010, page numbers are called "slide numbers." To remove slide numbers from an entire PowerPoint 2010 presentation or from a single slide, you must use the Slide Number tool.