/ Collective numbers - dwoje, troje, czworo
I studied, i.e. learned, Polish while simultaneously dabbling in Russian. At the time, almost twenty years ago, I found Polish a snap but Russian a killer:-) Fast forward twenty years, I'm now starting to learn Albanian, and thought that Polish had the slipperiest of grammar! LOL Well, Polish may have it's numerical nightmares for foreigners, but Albanian for instance, has both definite and indefinite noun endings for both given as well as place names!!!Polish names are conjugated, true enough. But I suppose, every language has its own idiocyncracies:-) Am happy to be of further assistance!
Polish a snap? Yeah right. ;) Russian grammar is significantly easier than Polish in almost every aspect. Definite forms for place names sounds kind of weird, but it's hardly anything that would make a language all that much more difficult. I don't really know anything about Albanian, but of all the languages I know something about, I would rate them like below in terms of grammatical complexity where 1 is as easy as possible and 10 something totally off the charts:
English: 2/10 - Can't get much easier than this. No cases (I don't even count genitive), no genders...
Swedish: 3/10 - 2 genders, no cases, verbs don't have to agree with anything
German: 5/10 - 3 genders, 4 cases, lots of exceptions, but not quite in the same league as Slavic languages
Russian: 7.5/10 - 3 genders, 6 cases, lots of inflections
Polish: 9/10 - 3 genders, 7 cases, 2 plural forms, even more different kinds and more complex inflections. Honestly I don't know how it could get much harder.
I'm sure there are harder languages than Polish, like Navajo, or maybe Basque, but all in all Polish grammar is really among the hardest out there, at least when it comes to major languages.