Keynote: How to Add Page Numbers to All Slides

To automatically update page numbers on slides as you create or arrange them, add a page number to the master slide(s). Follow these steps:

1. Open Keynote.
2. Open your document or create a new document.
3. Choose View > Show Master Slides.
4. Select the master slide in the Master Slides column.
5. Choose View > Show Inspector.
6. Select the "Show Slide #" checkbox in the Layout pane of the Master Slide inspector window.
7. Position the page number in the master slide

Repeat steps 4 through 7 for each master slide you want to number.