The second thing that you probably want to know in a foreign language is how to say goodbye. Here things are a bit easier compared to hello.
For the formal way we have 3 different expressions:
viso gero - goodbye
geros dienos - have a good day
sudie - farewell, goodbye
For the informal way we also have 3 different expressions:
iki ( pasimatymo* ) - see you ( next time )
*by the way - pasimatymas means a date. So literally iki pasimatymo means: see you in a next date
viso - bye ( simple, friendly )
ate - bye ( compared to viso sounds even more informal )