Function Any2Dec(ByVal otherBaseNumber As String, ByVal base As Integer) As Long
Dim index As Long
Dim digits As String
Dim digitValue As Long

' check base
If base < 2 Or base > 36 Then Err.Raise 5
' get the list of valid digits
digits = Left("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ", base)

' convert to decimal
For index = 1 To Len(otherBaseNumber)
' get the digit's value
digitValue = InStr(1, digits, Mid$(otherBaseNumber, index, 1), _
vbTextCompare) - 1
' error if invalid digit
If digitValue < 0 Then Err.Raise 5
' add to running result
Any2Dec = Any2Dec * base + digitValue
Next

End Function