Function NbCarac(Plage As Range, lettre As String) As Integer
Application.Volatile
Dim i#, j#, c As Range
NbCarac = 0
For Each c In Plage.SpecialCells(xlCellTypeConstants, 23)
i = 0: j = 0
Do
i = InStr(i + 1, c, " " & lettre)
If i <> 0 Then
j = i
Do While Mid(c, j + 1, 1) = lettre
j = j + 1
Loop
NbCarac = NbCarac + j - i '+ 1
i = j + 1
End If
Loop Until i = 0
Next
End Function