Dans macro sélection de cellules actives

Option Explicit

Sub SelectionneCellule()

    Dim Texte As String, Titre As String
    Dim Plage As Range, Cellule As Range
    Dim Somme As Long
    
    Titre = "Cellules cibles"
    Texte = "Choisir les cellules :"
    Set Plage = Application.InputBox(Texte, Titre, Type:=8)
    
    Somme = 0
    For Each Cellule In Plage
        Somme = Somme + Cellule.Value
    Next Cellule
    
    MsgBox Somme
    
End Sub
'

Option Explicit

Private Sub Worksheet_SelectionChange(ByVal Target As Range)

    Dim Plage As Range, Intersection As Range, Cellule As Range
    Dim Section As String, ToutesLesCells As Range
    
    Set Plage = Range("A6")
    
    Set Intersection = Application.Intersect(Plage, Target)
    
    Section = ""
    If Not (Intersection Is Nothing) Then
        For Each Cellule In UsedRange
            If Not (IsEmpty(Cellule.Value)) Then
                Section = Section & Cellule.Address & ","
            End If
        Next Cellule
        Section = Mid(Section, 1, (Len(Section) - 1))
        Set ToutesLesCells = Range(Section)
        ToutesLesCells.Select
    End If
    
    Set Plage = Nothing
    Set Intersection = Nothing
    Set ToutesLesCells = Nothing

End Sub
'