Преобразование из любой системы исчисления в десятичную

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim a As Integer 'из 10 в 2
        a = Val(TextBox1.Text)
        Label1.Text = Convert.ToString(a, 2)
 
    End Sub
 
    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        Dim a As Integer 'из 10 в 16
        a = Val(TextBox1.Text)
        Label2.Text = Convert.ToString(a, 16)
    End Sub
 
    Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
        Dim a As Integer
        a = Val(TextBox1.Text) 'из ? в 10
        Label3.Text = Convert.ToString(10, a)
    End Sub

 TextBox2.Text = System.Convert.ToByte(TextBox1.Text, 2)

Function Convert(ByVal number As String, ByVal srs As Integer, ByVal targ As Integer) As String
        Dim Sc As String = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        If srs <= 1 Or srs > 36 Or targ <= 1 Or targ > 36 Then MsgBox("Error") : Return "0"
        Dim Z As Integer
        For i = 1 To Len(number)
            Dim k As Integer = InStr(Sc, Mid(number, i, 1)) - 1
            Z = Z * srs + k
        Next
 
        Do While (Z > 0)
            Convert = Mid(Sc, (Z Mod targ) + 1, 1) & Convert
            Z = Z \ targ
        Loop
    End Function
 
    Sub Test()
        Dim s = "11111111"
        MsgBox(Convert(s, 2, 10))
    End Sub