| I'm not a linguist so I can't send any articles that explain the origins of this mess. But here are actual examples of usage: dwa ptaki (two birds) dwoje ludzi (two persons) dwie dziewczyny (two girls) idę z dwiema dziewczynami (I'm walking with two girls) dałem kwiaty dwom dziewczynom (I gave flowers to two girls) kanapa dla dwojga (a sofa for two - gender unspecified) dałem śniadanie dwojgu (I served breakfast for two others) dwójka to słaba ocena (two is a poor grade) dwie dwójki to razem czwórka (two twos are four altogether) dostałem dwójkę z Fizyki (I got a two in physics) z dwójką przyjaciół poszliśmy do klubu (we went to the club with two friends) w autobusie dwójce siedział pijany facet (there was a drunk fella on bus number two) O, dwójko, nie wracaj już do mojego dziennika (Oh, two, don’t come back to my gradebook again) Of course I don't consciously think about when to use the right conjugation. I just know it by heart and it's second nature but I can only give coherent rules to some of them. |
It's probably because Polish, unlike English and most Western European languages, has a case system (where nouns are modified to indicate their function, i.e subject, object, instrument, etc).
That's a pretty common feature in grammatically conservative Indo-European languages. Other living Indo-European languages, like Lithuanian, are even more conservative and have preserved nearly the entire case system of their ancestor.