How many slides can a presentation hold?

As far as I know, nobody knows the answer to this question. The answer may be "It depends"

But if you feel bold, you could try running this macro. Start with a presentation containing only one blank slide.
The code below will keep adding slides (and putting a text box with the slide number on each) until it reaches the value you've chosen for MaxSlides. Or until PowerPoint crashes? Dunno. As I said, this is for the bold.

Sub MaxItOut()

Dim x As Long
Dim MaxSlides As Long

MaxSlides = 100 ' or however far you want to take this
                ' Longs can take values up to 2,147,483,647
                ' Speaking of Long, it might take a LONG time to run the macro if you max it

' Assuming there's already one slide in the presentation
For x = 2 To MaxSlides
    ActivePresentation.Slides.Add x, ppLayoutBlank
    With ActivePresentation.Slides(x)
        With .Shapes.AddTextbox(msoTextOrientationHorizontal, 100, 100, 200, 200)
            .TextFrame.TextRange.Text = CStr(x)
        End With
    End With
Next x

End Sub

See How do I use VBA code in PowerPoint? to learn how to use this example code.

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