Validar RUT!
Excel

Function dv(a)
    j = 2
    For i = 0 To Len(a) - 1
        aux = aux + Val(Mid$(a, Len(a) - i, 1)) * j
        If j > 6 Then
            j = 2
        Else
            j = j + 1
        End If
    Next i
    aux1 = 11 - (aux Mod 11)
    If aux1 < 10 Then
        dv = aux1
    Else
        dv = "K"
    End If
End Function