The number 3 (both masculine and feminine trys) is also declined differently:

Nominative case: trys
Genitive case (of): trijų
Dative case (to/for): trims
Accusative case: tris
Instrumental case (using): trimis
Locative case (in): trijuose (masculine), trijose (feminine)


Jis laukė tavęs tris dienas. He was waiting for you for three days.
Tokiems trims greitiems automobiliams reikėjo gero vairuotojo. For such three fast cars a good driver was needed.
Mūsų mokykloje buvo tik trys mokytojos. Only three female teachers were in our school.