Calculating elapsed time between starting and closing excel

[mokhtar]

hi all
i'm try Calculating elapsed time between starting and closing excel with 2 codes

Private Sub Workbook_Open()

Dim StartTime As Double

'Remember time when macro starts
  StartTime = Timer

End Sub

Private Sub Workbook_BeforeClose(Cancel As Boolean)

Dim StartTime As Double
Dim SecondsElapsed As Double

'Determine how many minutes  from  starting  and closing excel 
MinutesElapsed = Format((Timer - StartTime) / 86400, "hh:mm:ss")                 
'Notify user in minutes 

MsgBox " This worbook open  for " & MinutesElapsed & " minutes", vbInformation     

End Sub

Any suggestions.... my experience of macros is limited

Thanks in advance for all your help!!