Let's focus on the Nominative for now (this also works when Acc.=Nom). Russian numbers may seem a bit weird. The case of the noun depends on the last word of the number:
| last word | means | Case | example |
|---|---|---|---|
| оди́н (одна́, одно́, одни́ ) | 1 | Nom. sg. | оди́н дом, одна́ ма́ма, два́дцать одно́ окно́, оди́н сто́л |
| два (две), три, четы́ре | 2, 3, 4 | Gen. sg. | две ко́шки, два стола́, три ма́льчика, три́дцать четы́ре стола́ |
| Larger than that | 5, 6, 12, 100 etc. | Gen. pl. | пять ко́шек, пять ма́льчиков, два́дцать пять ко́шек, миллио́н ко́шек |
Just like English, Russian has words for eleven through nineteen, so they fall into the "larger" category.
Genitive plural has a rather bizarre set of patterns, so a separate skill later on will teach you how to make it for most nouns.
The Dative forms of он, она and они are ему, ей, им respectively.
Why are Russian numbers so strange? Well, for 2-3-4 these are the remnants of Dual number (which is between the singular and the plural). As for the larger numbers, they are essentially "nouns": a heap of cats, a lot of cats, a thousand... of cats.
Russian uses two words for "now". One is «сейчас», which means "now, at the moment", and describes the current moment in a neutral manner, often implying that things change and the state described is attributed to this particular moment. It can change soon:
Теперь is the "now" you use when things are different from "before". You imply that the situation has changed. It is also associated with a more prolonged period of time, i.e. the state of affairs is different from before, and will stay so for now:
The noun «время» ("time") belongs to a really small class of neuter nouns. Its Genitive form is времени, and all other oblique forms also retain the -ен part.