Option Explicit

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    If Selection.Count = 1 Then
        If Not Intersect(Target, Range("D4")) Is Nothing Then
            call Area(Range("A1").Value, Range("A2").Value)
        End If
    End If
End Sub

Sub Area(x As Double, y As Double)
  MsgBox x * y
End Sub

#======================
Option Explicit

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    If Selection.Count = 1 Then
        If Not Intersect(Target, Range("D4")) Is Nothing Then
            call OpenPDFPage()
        End If
    End If
End Sub

#=====
Option Explicit

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    If Selection.Count = 1 Then
        If Not Intersect(Target, Range("D4")) Is Nothing Then
            Dim PrgPath As String
            Dim PdfFile As String
            Dim PageCode As String
            Dim PageNo As Integer

            PrgPath = "C:\Program Files\Adobe\Reader 11.0\Reader\AcroRd32.exe"
            PdfFile = Range("A1").Value
            PageCode = "/A page="
            PageNo = Range("A2").Value
            Shell PrgPath & " " & PageCode & PageNo & " " & PdfFile, 1
        End If
    End If
End Sub

#======
Sub Replace()

    Dim rng As Range, cell As Range
    Set rng = Sheets("Sheet1").Range("A1:A629")

    For Each cell In rng
        cell = WorksheetFunction.Substitute(cell, ",", ";")
    Next
End Sub

#=====
Sub ReplaceText()

    For Each c In Sheets("Sheet1").Range("A1:A629").Cells

      c = Replace(c.Value, ",", ";")

    Next c

End Sub
#=====
http://stackoverflow.com/questions/32296386/how-to-pass-a-value-from-one-sub-to-another-in-excel-vba
pass a value from one sub to another in Excel VBA
#=====
http://stackoverflow.com/questions/18968856/vba-paste-range
paste range
#=====
Function Area(Length As Double, Width As Double)
    Area = Length * Width
End Function
#=====
#=====