The genitive plural deeper

How many books? Many books. Few friends. The case that runs Russian shopping.

We met genitive plural briefly with numbers (5+ → пять книг). It's also the case after quantity words like много (a lot), мало (few), несколько (several), сколько (how many). The endings are surprisingly varied — here's the system.

Masculine ending in a hard consonant: -ов

Стол → столов. Друг → друзей (irregular but common). Студент → студентов. День → дней. Час → часов. Most masculines take -ов. Soft-sign masculines (день, рубль) take -ей.

Feminine in -а: drop the -а

Книга → книг. Мама → мам. Школа → школ. Комната → комнат. Песня → песен (with vowel insertion to break consonant clusters). If the result has a hard consonant cluster, Russian inserts -о- or -е-. Don't memorize the rule — recognize the form.

Neuter in -о: drop the -о

Окно → окон. Слово → слов. Море → морей. Vowel-insertion happens here too: окно → окон (not окн).

Quantity expressions

All of these take genitive plural: - много (a lot of): много книг - мало (few/little): мало времени - несколько (a few/several): несколько друзей - сколько (how many): сколько часов? These aren't 'real' nouns — they're quantifiers, and they trigger the genitive.

Examples

У меня много друзей.

I have a lot of friends.

В Москве мало времени.

In Moscow there's little time.

Время is irregular — its genitive is времени.

Несколько хороших книг.

Several good books.

Adjective also in gen. pl: -их.

Сколько у тебя рублей?

How many rubles do you have?

Soft-sign masculine: рублей.

Я прочитал пять книг.

I read five books.

After 5+ → genitive plural.

У нас нет окон.

We have no windows.

Negation + genitive plural.