I may have started it with the party security riddle I made, but now there's around 25 of them! I didn't intend for that to happen... Is there any problem with this [Part #] trend on Puzzling.SE?

This party is so popular! So just like before, you want the spaghetti recipe yada yada yada... basically, you want to get in to the party. The first guest arrives, the security guard says "6". The guest goes away to check the answer, but soon returns, saying "3", and is admitted. The second gu...