>Hi All,
>
>I do remember that in previous versions of Excel it was theoritacally possible to write your own formula and call it from any cell the same way one calls a built-in forumula. All this without having to trigger a macro manually. Is it still possible with Office 2000 version of Excel? If yes, how can it be done?
>
>Thanks in advance,
>
>Jonathan

Yes it is still possible:
Create a new workbook (xls file) and save it

From Excel Menu:
Tools->Macro->Visual Basic Editor

From VB Editor menu:
Insert->Module

Double click on Module1 added in project explorer pane.
Type your VBA function, e.g.:
Public Function PI2()
PI2 = 355 / 113
End Function

Use your function, like you will use any other native Excel function.
Hope This Helps