Sub TotalTimes()
' Copyright/Last Edited 20 January, 2015 by Stepen Rindsberg dba PPTools

Dim oSld As Slide
Dim strMessage As String
Dim lngTotalTime As Long

' Use this to collect times for ALL slides:
For Each oSld In ActivePresentation.Slides
' Or comment it out and uncomment this to get just the selected slides:
' For Each oSld in ActiveWindow.Selection.SlideRange
    strMessage = strMessage _
        & CStr(oSld.SlideNumber) _
        & vbTab _
        & CStr(oSld.SlideShowTransition.AdvanceTime) _
        & vbCrLf
    lngTotalTime = lngTotalTime + oSld.SlideShowTransition.AdvanceTime
Next oSld

' Comment these out if you don't want to see them
MsgBox strMessage
MsgBox ("Total time: " & CStr(lngTotalTime))

' And if you want to write the results to a text file:
Dim FileNum As Integer
Dim FileName As String

' Edit this to suit, especially if you use a Mac:
' As written, it'll pick up your TEMP folder location automatically:
FileName = Environ$("TEMP") & "\" & "SlideTimings.txt"

FileNum = FreeFile()
Open FileName For Output As FileNum
Print #FileNum, strMessage
Print #FileNum, "Total time: " & CStr(lngTotalTime)
Close #FileNum
' view the file in notepad
Call Shell("Notepad.exe " & FileName, vbNormalFocus)
' or if you use a mac, comment that out and open the file in any text editor you like

End Sub