An auto-entered serial number setting on your sort field will always enter the next value in the series--but this will be over all the records in the portal's table, not just those visible in the portal. That will be sufficient for sorting, but won't "look pretty". You can show a perfect numerical sequence if you keep that field as a serial number but add a layout text symbol for the record number to the portal row for "display" purposes. In FileMaker 11 and older, this is the @@ symbol. In Filemaker 12, a different symbol is used. You can select the record number symbol from the Insert menu to insert it into a text block in your portal row.