Public Class Form1
 
    Dim Max As Integer = 99
    Dim Xmin As Integer = 0
    Dim x As Integer = 0
    Dim Número As Double
 
    Private TextBoxes As TextBox() = {Nothing}
    Private Result1 As Int32(), Result2 As Int32(), Result3 As Int32()
    Private _textBox As Object
    Private _getNumbersNotInRange As Object
 
    Private Property ListBox1Count As Integer
 
    Private Property Calcular As Object
 
    Private Property TextBox(ByVal TextBoxCount As Short) As Object
        Get
            Return _textBox
        End Get
        Set(ByVal value As Object)
            _textBox = value
        End Set
    End Property
 
 
    ReadOnly Property Num1 As Int32
        Get
            Return CInt(TextBox1.Text)
        End Get
    End Property
 
    ReadOnly Property Num2 As Int32
        Get
            Return CInt(TextBox2.Text)
        End Get
    End Property
    ReadOnly Property Num3 As Int32
        Get
            Return CInt(TextBox3.Text)
        End Get
    End Property
 
    Private Property GetNumbersNotInRange(ByVal Result11 As IEnumerable(Of Integer), ByVal Xmin As Integer, ByVal XMax As Integer) As Object
        Get
            Return _getNumbersNotInRange
        End Get
        Set(ByVal value As Object)
            _getNumbersNotInRange = value
        End Set
    End Property
 
 
    Private Sub Sumar(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click
 
 
 
        Result1 = {Num1 + 10, Num1 + 20, Num1 + 30} _
                  .Distinct().ToArray ' Elimino duplicados
 
        Result2 = {Num2 + 10, Num2 + 20, Num2 + 30} _
                  .Distinct().ToArray ' Elimino duplicados
 
        Result3 = {Num3 + 10, Num3 + 20, Num3 + 30} _
                  .Distinct().ToArray ' Elimino duplicados
        ' primero concatenas y eliminas duplicados en el primer array:
 
        Dim Result11 As IEnumerable(Of Integer) =
        (Result1.Concat(Result2).Concat(Result3).
          Distinct)
 
 
        ' Dim arregloSumas() As Integer = {10, 15, 20, 25, 30}
        Dim numerosFaltantesdelRango() As Integer = {}
        Dim rango_min As Integer = 0, rango_max As Integer = 99
        Dim tamanio As Integer
        Dim val As Integer
 
 
        Dim test As Integer
        For i = rango_min To rango_max
            val = i
            If Array.Exists(Result11.Cast(Of Object).ToArray, Function(value As Integer) value = val) = False Then 'Compruebo si el valor de i no aparece en el arreglo de las sumas
 
                test += 1
                tamanio = UBound(numerosFaltantesdelRango) + 1
                ReDim Preserve numerosFaltantesdelRango(tamanio)
                numerosFaltantesdelRango(tamanio) = val 'Agrego el valor al arreglo
 
            End If
        Next
 
        ListBox1.Items.AddRange(numerosFaltantesdelRango.Cast(Of Object).ToArray)
 
    End Sub
End Class