This example shows how changing the first slide number affects the slide number of a specific slide.
With Application.ActivePresentation
.PageSetup.FirstSlideNumber = 1 'starts slide numbering at 1
MsgBox .Slides(2).SlideNumber 'returns 2
.PageSetup.FirstSlideNumber = 10 'starts slide numbering at 10
MsgBox .Slides(2).SlideNumber 'returns 11
End With
This example hides the slide number on slide two in the active presentation if the number is currently visible, or it displays the slide number if it's currently hidden.
With Application.ActivePresentation.Slides(2) _
.HeadersFooters.SlideNumber
If .Visible Then
.Visible = False
Else
.Visible = True
End If
End With