Public Sub Summary_calculation()

   Dim wb As Workbook
   Dim ws As Worksheet
   Dim endrow As Integer
   Dim temprow As Integer
   Dim tempcol As Integer
   Dim i As Integer
   Dim totalrec As Integer
   Dim tmpSheet As Worksheet
   Dim SKUCol As Integer
   Dim SKUName As String
   Dim tmpSheetrow As Integer
   Dim tmpcol As Integer
   Dim tmpQty As Double

   Set wb = ActiveWorkbook
   Set ws = wb.Sheets("Summary")

   SKUCol = 3

   totalrec = ws.Cells(startrow, 1).CurrentRegion.Rows.Count - 1

   For i = 1 To totalrec

      SKUName = ws.Cells(i + startrow, SKUCol).Value

      Set tmpSheet = wb.Sheets(SKUName)

      'tmpSheet.Activate (Got 1004 error whenever remove this line of code)

      tmpSheetrow = tmpSheet.Cells(startrow, Gapcol).CurrentRegion.Rows.Count + startrow - 1

      For tmpcol = 0 To 16
         With wb.Sheets(SKUName)

            ws.Cells(i + startrow, tmpcol + 4).Value = Application.WorksheetFunction.Sum(.Range(Cells(startrow + 1, PropStartcol + tmpcol), Cells(tmpSheetrow, PropStartcol + tmpcol)))

         End With
      Next tmpcol
      ws.Cells(1, 10) = Format(i / totalrec, "00%")
      DoEvents
   Next i

End Sub