Private Sub Command1_Click()
 Text3.Text = Plus(Text1.Text, Text2.Text)
End Sub
 
Function Plus(Wert1 As String, wert2 As String) As String
 Dim a, b, x
 Dim Wert As String
 Dim ErgWert As String
 Dim Erg As Integer
 Dim Merke As Integer
 
    If Len(Wert1) >= Len(wert2) Then
        ErgWert = Wert1
        Wert = wert2
    Else
        ErgWert = wert2
        Wert = Wert1
    End If
 
    For i = 1 To Len(ErgWert) - Len(Wert)
        Wert = 0 & Wert
    Next i
 
    Merke = 0
 
    For i = Len(Wert) To 1 Step -1
        Erg = CInt(Mid(ErgWert, i, 1)) + CInt(Mid(Wert, i, 1))
        Erg = Erg + Merke
        Mid(ErgWert, i, 1) = CInt(Right(Erg, 1))
 
        If Len(Trim(Erg)) = 2 Then
            Merke = Left(Erg, 1)
        Else
            Merke = 0
        End If
    Next i
 
    If Merke <> 0 Then _
    ErgWert = Merke & ErgWert
    Plus = ErgWert
End Function