[Zubersoft]

There are several ways to go about doing this. One option would be to use the Custom field to store the number, and change the song formatting in the settings to be "%TITLE% - %CUSTOM%" or some other variant that shows the custom field value. Then you will be able to see the number for every song on the library screen. To quickly filter on number, you could just type the number into the search box at the top.

Mike