Thanks a lot for your suggestions. I know the problem can be solved using purgechar etc., but as said I wonder if there is a way to do it by ONLY using num#. Actually the manual uses the example num#(A,'abc#,#') which is obviously able to mask out the leading string 'abc'. So I imagined a num#(myField,'#_.#' ..) might do the job. I tried several variations, but without any success.