Выполнение арифметических операций в разных системах счисления

Function Dec_To_N_Schisl(n As Integer, i1 As Variant) As String
' Переводит десятичное число i1 в систему счисления N.
Dim ik As Long, it As Long, ostatok As Integer, Zn As String
Dim Chislo As String
i1 = CLng(i1)
ik = 0
it = i1
Chislo = ""
If n <= 1 Then Exit Function
Do
    ostatok = it Mod n
    it = it \ n
    Select Case ostatok
        Case 0 To 9
          Zn = Trim(CStr(ostatok))
        Case 10 To 37
          Zn = Chr(55 + ostatok)
        Case Else
          Zn = "#"
    End Select
    Chislo = Zn & Chislo
Loop While it > 0
Dec_To_N_Schisl = Chislo
End Function
 
Function N_Schisl_To_Dec(n As Integer, ChisloN As Variant) As Long
' Переводит число ChisloN из системы счисления N в десятичное .
Dim ik As Long, Zn As String
Dim Chislo10 As Long
ChisloN = UCase(Trim(CStr(ChisloN)))
k = Len(ChisloN)
Chislo10 = 0
For i = 1 To k
    Zn = Mid(ChisloN, k + 1 - i, 1)
    Select Case Zn
        Case "0" To "9"
          ik = Val(Zn)
        Case "A" To "Z"
          ik = Asc(Zn) - 55
    End Select
    Chislo10 = Chislo10 + n ^ (i - 1) * ik
Next
N_Schisl_To_Dec = Chislo10
End Function