on a username, you can only have letters numbers, dashes, and underscores. you cant have a username that is JUST numbers. on a project, its one string of only numbers a comment on a profile is the username string, then the comment string, which is only numbers a studio is the same as a profile. most usernames will either have all lowercase or all uppercase letters still confused? check this out https://scratch.mit.edu/projects/1288535242/