Salut stagiiaireVannes, Lauange,
une façon de faire, sans plus..., à tester...
Private Sub Worksheet_Change(ByVal Target As Range)
'
Dim tTab, tSplit
'
Application.EnableEvents = False
tTab = UsedRange
'
For x = 1 To UBound(tTab, 1)
For y = 1 To UBound(tTab, 2)
If IsNumeric(Left(tTab(x, y), 1)) Then tTab(x, y) = Split(tTab(x, y), "-")(1)
Next
Next
'
UsedRange = tTab
Application.EnableEvents = True
'
End Sub
A+