Option Explicit
Sub Tst()
Dim iLastRow As Long, i As Long
Dim Pos1 As Long, Pos2 As Long
Dim Chaine As String
Application.ScreenUpdating = False
Columns("A:A").Clear
iLastRow = Range("B65536").End(xlUp).Row
For i = 1 To iLastRow
Pos1 = InStr(Cells(i, 2), "("): Pos2 = InStr(Cells(i, 2), ")")
If Pos1 > 0 And Pos2 > 0 Then
Chaine = Mid(Cells(i, 2), Pos1 + 1, Pos2 - Pos1 - 1)
If IsNumeric(Chaine) Then Cells(i, 1) = CLng(Chaine)
End If
Next i
Range("C1").Select
Application.ScreenUpdating = True
End Sub