PowerPoint slide numbers not showing: check the layout and master

In PowerPoint for Windows, open Insert > Slide Number. On the Slide tab, enable Slide number and select Apply to All. If only the title slide is missing a number, check whether Don’t show on title slide is enabled. Leave that option on if the omission is intentional.

Select a slide that lacks its number, then open View > Slide Master. PowerPoint opens the layout used by that slide. On the Slide Master tab, find the Master Layout group and enable Footers. The footer placeholders should become visible. This setting controls whether the layout can show footer information; entering a number in a normal text box does not restore automatic numbering.

If the layout does not accept the Footers setting, select its parent slide master, the larger thumbnail above the indented layouts. Open Master Layout, enable Date, Slide number and Footer, and confirm. Then return to the affected child layout and enable Footers there. Presentations with multiple themes can have multiple masters, so inspect the master belonging to the problem slide.

Close Master View and check a slide from each affected layout. Reapply the numbering setting if needed. If the number is in the wrong place, move its placeholder on the appropriate slide master rather than adding a typed number to each slide. These steps target desktop PowerPoint; the web app uses a Footer pane and does not provide the same master-editing workflow.