Rechnen mit sehr großen Zahlen (über 100.000 Stellen) mit Komma

Module MATHs
    Public Function LTrim0(ByVal strVar As String) As String
        Do Until Len(strVar) = 1 Or Left$(strVar, 1) <> "0"  
            strVar = Mid$(strVar, 2)
        Loop
        LTrim0 = strVar
    End Function

    Public Function Add(ByVal strNo1 As String, ByVal strNo2 As String) As String
        Dim bytSum As Byte
        Dim bytCarry As Byte
        Dim lngMax As Long
        Dim lngVar As Long
        Dim strSum As String = ""  

        strNo1 = LTrim0(strNo1)
        strNo2 = LTrim0(strNo2)
        lngMax = IIf(Len(strNo1) > Len(strNo2), Len(strNo1), Len(strNo2))
        strNo1 = Right$(New String("0", lngMax) & strNo1, lngMax)  
        strNo2 = Right$(New String("0", lngMax) & strNo2, lngMax)  
        For lngVar = Len(strNo1) To 1 Step -1
            bytSum = Val(Mid$(strNo1, lngVar, 1)) + Val(Mid$(strNo2, lngVar, 1)) + bytCarry
            strSum = bytSum Mod 10 & strSum
            bytCarry = bytSum \ 10
        Next lngVar
        If bytCarry Then strSum = bytCarry & strSum

        Return strSum
    End Function

    Public Function Divide(ByVal strNo1 As String, ByVal strNo2 As String) As String
        Dim bytQuo As Byte
        Dim lngVar As Long
        Dim strQuo As String = ""  
        Dim strDiv As String = ""  
        Dim strVar As String = ""  

        strNo1 = LTrim0(strNo1)
        strNo2 = LTrim0(strNo2)
        lngVar = Len(strNo2)
        strDiv = Left$(strNo1, lngVar)
        Do While lngVar <= Len(strNo1)
            strVar = Subtract(strDiv, strNo2)
            bytQuo = 0
            Do While Left$(strVar, 1) <> "-"  
                bytQuo = bytQuo + 1
                strVar = Subtract(strVar, strNo2)
            Loop
            strQuo = strQuo & CStr(bytQuo)
            lngVar = lngVar + 1
            strDiv = Subtract(strNo2, Mid$(strVar, 2)) & Mid$(strNo1, lngVar, 1)
        Loop

        Return LTrim0(strQuo)
    End Function

    Public Function Modulo(ByVal strNo1 As String, ByVal strNo2 As String) As String
        Return Subtract(strNo1, Multiply(strNo2, Divide(strNo1, strNo2)))
    End Function

    Public Function Multiply(ByVal strNo1 As String, ByVal strNo2 As String) As String
        Dim bytPrd As Byte, bytCarry As Byte
        Dim lngVar1 As Long, lngVar2 As Long
        Dim strPrd As String, strVar As String

        strNo1 = LTrim0(strNo1)
        strNo2 = LTrim0(strNo2)

        If Len(strNo1) > Len(strNo2) Then
            strVar = strNo1
            strNo1 = strNo2
            strNo2 = strVar
        End If

        strPrd = "0"  

        For lngVar1 = Len(strNo1) To 1 Step -1
            strVar = New String("0", Len(strNo1) - lngVar1)  
            bytCarry = 0
            For lngVar2 = Len(strNo2) To 1 Step -1
                bytPrd = Mid$(strNo1, lngVar1, 1) * Mid$(strNo2, lngVar2, 1) + bytCarry
                strVar = bytPrd Mod 10 & strVar
                bytCarry = bytPrd \ 10
            Next lngVar2
            If bytCarry Then strVar = bytCarry & strVar
            strPrd = Add(strPrd, strVar)
        Next lngVar1

        Return strPrd
    End Function

    Public Function Subtract(ByVal strNo1 As String, ByVal strNo2 As String) As String
        Dim bytDif As Byte
        Dim bytCarry As Byte
        Dim lngVar As Long
        Dim strDif As String = ""  
        Dim strVar As String = ""  

        strNo1 = LTrim0(strNo1)
        strNo2 = LTrim0(strNo2)
        If Len(strNo1) < Len(strNo2) Or (Len(strNo1) = Len(strNo2) And strNo1 < strNo2) Then
            strVar = strNo1
            strNo1 = strNo2
            strNo2 = strVar
        End If
        strNo2 = Right$(New String("0", Len(strNo1)) & strNo2, Len(strNo1))  
        For lngVar = Len(strNo1) To 1 Step -1
            bytDif = Val(Mid$(strNo1, lngVar, 1)) - Val(Mid$(strNo2, lngVar, 1)) - bytCarry + 10
            strDif = bytDif Mod 10 & strDif
            bytCarry = 1 - bytDif \ 10
        Next lngVar
        strDif = LTrim0(strDif)
        If strVar > "" Then strDif = "-" & strDif  
        Return strDif
    End Function
End Module