Sub a()
MsgBox FormatExposant([A1])
End Sub
Function FormatExposant(Cellule As Range) As String
Dim d As Double
Dim S As String
Dim i As Integer
S = CStr(Cellule.Value)
If Len(S) >= 12 Then
S = Left(S, 1) & "," & Mid(S, 2, 4) & "E+" & Len(S) - 1
End If
FormatExposant = S
End Function