Have code that reads (thanks to ozgrid)

Private Sub Workbook_SheetChange(ByVal Sh As Object, ByVal Target As Range)

If Not Intersect(Target, Range("c13:c22")) Is Nothing Then
ActiveCell.Offset(0, 2).Value = ActiveCell.Value * ActiveCell.Offset(0,
1).Value
End If

but that effects the range c13:c22 on all sheets; How do I keep it specific
to a particular sheet?

TIA