You need the two functions which I posted earlier (Bin2Dec & Dec2Bin).
And it only works for base 2, 8, 10, & 16.

Function CBase(sNumber As String, nToBase As Long, nFromBase As Long) As String
    Dim nNumber As Long
    Select Case nToBase
        Case Is = 2:    nNumber = Bin2Dec(sNumber)
        Case Is = 8:    nNumber = Val("&O" & sNumber)
        Case Is = 10:   nNumber = Val(sNumber)
        Case Is = 16:   nNumber = Val("&H" & sNumber)
    End Select
    Select Case nFromBase
        Case Is = 2:    CBase = Dec2Bin(nNumber)
        Case Is = 8:    CBase = CStr(Oct(nNumber))
        Case Is = 10:   CBase = CStr(nNumber)
        Case Is = 16:   CBase = CStr(Hex(nNumber))
    End Select
End Function