bạn chọn sheet muốn định dạng chọn view code sau đó dán code này Private Sub Worksheet_Change(ByVal Target As Range)
Dim str As String, r As Integer, c As Integer
If InStr(1, Target.Value, "/") Or Target.Value = "" Then Exit Sub
If Not Intersect(Target, Columns("B:B")) Is Nothing Then
str = Target.Text
r = Target.Row
c = Target.Column
str = Left(str, 2) & "/" & Mid(str, 3, 2) & "/" & Right(str, 4)
Cells(r, c).Value = str
Exit Sub
End If
End Sub
