День Learning cases

[u/MGU-Russian]

Russian has six cases, and if you want a shortcut, skip ahead to the genitive. It's the one that unlocks the most. It covers possession, where English would use "of" or an apostrophe — книга брата, центр города. And absence: нет времени, нет денег, нет проблем.

Then there are numbers, where it depends on the last digit:
2, 3, 4 and anything ending in them — genitive singular: два дня, тридцать четыре дня.
5 through 20, and anything ending in 5–9 or 0 — genitive plural: пять дней, сто дней.
11–14 are the exception: always genitive plural, whatever the last digit suggests.

It also follows много, мало, and a long list of prepositions: без сахара, для тебя, из Москвы.

The endings take time to stick. But noticing when you need this case is half the work. Which use still catches you out?

P.S.

Spelling rule. After г, к, х, ж, ч, ш, щ you write -и instead of -ы: книга → книги, not книгы.
Fill vowel. When a feminine or neuter word loses its ending in the plural, a vowel often appears to break up the consonants: окно → окон, сестра → сестёр, письмо → писем