Use powers of 2 to build the decimal number from a binary string. Extract powers of 2 from the decimal value to convert it into a binary string.

Public Function BinaryToDecimal(Binary As String) As Long
Dim n As Long
Dim s As Integer

    For s = 1 To Len(Binary)
        n = n + (Mid(Binary, Len(Binary) - s + 1, 1) * (2 ^ _
            (s - 1)))
    Next s

    BinaryToDecimal = n
End Function

Public Function DecimalToBinary(DecimalNum As Long) As _
    String
Dim tmp As String
Dim n As Long

    n = DecimalNum

    tmp = Trim(Str(n Mod 2))
    n = n \ 2

    Do While n <> 0
        tmp = Trim(Str(n Mod 2)) & tmp
        n = n \ 2
    Loop

    DecimalToBinary = tmp
End Function