Genitive With Numbers and Quantities (detailed) | Russian Grammar

Every price, every age, every quantity in Russian runs through one rule: numerals govern the genitive, and the shape of that genitive — singular or plural — depends on the number. This is the single most frequent grammatical operation in everyday Russian, so this page is deliberately drill-heavy: the goal is to overlearn the reflex until два рубля́ / пять рубле́й / мно́го рубле́й come out without a flicker of thought. The navigational summary lives at case after numbers and the formal government rule at the numeral government rule; this page is the deep mechanics — compounds, fractions, and the declining numeral.

The core split: 2–4 vs 5–20

When the whole numeral phrase is in the nominative (the subject or a plain count), here is the law:

Number ends in…	Noun goes…	Example
1	nominative singular (agreeing)	оди́н дом, одна́ кни́га
2, 3, 4	genitive singular	два до́ма, три кни́ги, четы́ре окна́
5–20 (and 0, and 5–9)	genitive plural	пять домо́в, де́сять книг, два́дцать о́кон

У меня́ два бра́та и три сестры́.

I have two brothers and three sisters. (2 → genitive singular бра́та; 3 → genitive singular сестры́)

В кла́ссе пять ма́льчиков и де́сять де́вочек.

There are five boys and ten girls in the class. (5 → genitive plural ма́льчиков; 10 → genitive plural де́вочек)

Э́то сто́ит два рубля́, а то — пять рубле́й.

This costs two roubles, and that one five. (рубль: 2 → genitive singular рубля́; 5 → genitive plural рубле́й)

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The mental drill that cracks Russian numbers: chant два рубля́ / пять рубле́й / мно́го рубле́й — genitive singular / genitive plural / genitive plural. Once that triplet is automatic for one noun, you can run it on any noun. This single contrast is worth more practice than any other case interaction in the language.

Why singular after 2–4? (the historical reason)

It feels backwards that two takes a singular. The honest answer: it's a fossil. Old Russian had a dual number (a special form for exactly two), and 2, 3, 4 patterned with it. When the dual died out, its form survived as what now looks like the genitive singular. So два до́ма isn't "two of a house" — it's the frozen remains of an old dual. You don't need the history to use the rule, but it explains why the logic feels alien: there isn't a tidy modern reason, only an old one.

Compounds: the LAST digit decides

For any number above 20, look only at the last digit and apply the same split. The big number's earlier parts are irrelevant to the noun's form:

Compound ends in…	Noun form	Example
…1	nominative singular	два́дцать оди́н рубль
…2, …3, …4	genitive singular	два́дцать два рубля́, три́дцать четы́ре кни́ги
…5–…9, …0	genitive plural	два́дцать пять рубле́й, со́рок книг

В кни́ге два́дцать одна́ страни́ца.

The book has twenty-one pages. (…1 → nominative singular страни́ца — note feminine одна́)

Биле́т сто́ит два́дцать два рубля́.

The ticket costs twenty-two roubles. (…2 → genitive singular рубля́)

В зда́нии три́дцать семь кварти́р.

There are thirty-seven flats in the building. (…7 → genitive plural кварти́р)

So 21 behaves like 1, 22–24 behave like 2–4, and 25–30 behave like 5–20. The pattern repeats every ten, forever.

The 11–14 exception

There is one trap: 11, 12, 13, 14 are always genitive plural, even though they "end in" 1, 2, 3, 4. They are the teens, and the teens all take the genitive plural. The last-digit rule resumes only from 21 onward:

В гру́ппе оди́ннадцать студе́нтов.

There are eleven students in the group. (11 → genitive plural студе́нтов, NOT singular — the teens are special)

Мне двена́дцать лет.

I'm twelve. (12 → genitive plural лет)

Прошло́ четы́рнадцать дней.

Fourteen days have passed. (14 → genitive plural дней, not дня)

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Memorise it as a clean island: 11–14 are genitive plural (оди́ннадцать книг, двена́дцать книг), even though 11 looks like "ends in 1". The look-at-the-last-digit shortcut only kicks in at 21. Inside 11–19 there is no choice to make — it's always genitive plural.

When the numeral phrase isn't nominative

Everything above assumes the count is in the nominative (a subject or bare quantity). The moment a preposition or another case takes over the whole numeral phrase, the picture changes: both the numeral and the noun decline into that case, and the special "genitive after the number" rule switches off. The number stops governing and starts agreeing.

Я прочита́л кни́гу за два дня́.

I read the book in two days. (за + accusative: but the count phrase два дня́ keeps gen sg дня́ here)

Мы говори́ли о трёх кни́гах.

We talked about three books. (о + prepositional: трёх and кни́гах BOTH prepositional plural — no genitive)

Я дал э́то пяти́ студе́нтам.

I gave it to five students. (dative: пяти́ + студе́нтам, both dative plural)

Кни́га с пятью́ глава́ми.

A book with five chapters. (instrumental: пятью́ + глава́ми)

Notice that in the oblique cases the noun goes plural in the relevant case (трёх кни́гах, пяти́ студе́нтам), regardless of whether the number is 2–4 or 5+. The singular-after-2–4 rule is a nominative-and-accusative-only phenomenon. The full declension of the numerals themselves is on the numeral government rule.

полтора́, "two and a half", and other halves

полтора́ ("one and a half", masc./neut.) and полторы́ (fem.) take the genitive singular, exactly like 2–4:

Я ждал полтора́ часа́.

I waited an hour and a half. (полтора́ + genitive singular часа́)

Оста́лось полторы́ неде́ли до о́тпуска.

There's a week and a half left until the holiday. (полторы́ + genitive singular неде́ли)

For "X and a half" you say два́ с полови́ной ("two with a half") and the noun follows the whole number's rule — here the два drives it to the genitive singular:

Э́то ве́сит два с полови́ной килогра́мма.

It weighs two and a half kilograms. (два с полови́ной → genitive singular килогра́мма, following два)

Fractions and decimals → genitive singular

This is the elegant part. After a fraction or a decimal, the counted noun stands in the genitive singular — because the noun is grammatically governed by the fraction-noun (деся́тых = "tenths", тре́ти = "thirds"), and a fraction is "a part of" one whole:

Две це́лых пять деся́тых проце́нта.

Two point five percent (2.5%). (decimal → genitive singular проце́нта, not проце́нтов)

Тре́ть населе́ния живёт в города́х.

A third of the population lives in cities. (тре́ть → genitive singular населе́ния)

Полови́на гру́ппы не пришла́.

Half the group didn't show up. (полови́на → genitive singular гру́ппы)

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The rule of thumb for fractions and decimals: read the decimal aloud and the noun matches the last fraction word. Две це́лых пять деся́тых ends in деся́тых ("tenths") — a quantity word that, like all fractions, demands the genitive singular of the thing measured: …проце́нта. So a price of 2.5% is две це́лых пять деся́тых проце́нта, never …проце́нтов.

A shopping-list workout

Run your eye over a real list and tag each form — this is the reflex you're building:

Купи́: два кило́ карто́шки, три огурца́, пять помидо́ров, де́сять яи́ц и полтора́ ли́тра молока́.

Buy: two kilos of potatoes, three cucumbers, five tomatoes, ten eggs and a litre and a half of milk. (два кило́ → gen sg; три огурца́ → gen sg; пять помидо́ров → gen pl; де́сять яи́ц → gen pl; полтора́ ли́тра → gen sg)

У нас два́дцать два го́стя, зна́чит, ну́жно два́дцать два сту́ла и со́рок четы́ре таре́лки.

We've got twenty-two guests, so we need twenty-two chairs and forty-four plates. (…2 → gen sg го́стя, сту́ла; …4 → gen sg таре́лки)

Both sentences pivot on the same instant decision — look at the number, pick singular or plural genitive. Quantity words (мно́го, ма́ло, не́сколько) work on a related but distinct principle (count vs mass, not last digit); they live on genitive after quantity words. Keep the two systems mentally separate: numbers split by digit, quantity words split by countability.

Common Mistakes

❌ У меня́ два бра́тья.

Incorrect — 2 takes the genitive SINGULAR, not the plural: брат → бра́та.

✅ У меня́ два бра́та.

I have two brothers. (2 → genitive singular бра́та)

❌ В кла́ссе пять студе́нта.

Incorrect — 5 takes the genitive PLURAL, not the singular: студе́нт → студе́нтов.

✅ В кла́ссе пять студе́нтов.

There are five students in the class. (5 → genitive plural студе́нтов)

❌ Мне оди́ннадцать рубля́.

Incorrect — 11–14 are always genitive PLURAL despite ending in 1: рубль → рубле́й.

✅ Оди́ннадцать рубле́й.

Eleven roubles. (the teens are always genitive plural)

❌ Два́дцать одна́ страни́ц.

Incorrect — a compound ending in 1 takes the NOMINATIVE singular (and одна́ agrees in gender): страни́ца.

✅ Два́дцать одна́ страни́ца.

Twenty-one pages. (…1 → nominative singular страни́ца)

❌ Две це́лых пять деся́тых проце́нтов.

Incorrect — after a decimal/fraction the noun is genitive SINGULAR: проце́нта.

✅ Две це́лых пять деся́тых проце́нта.

2.5 percent. (decimal → genitive singular проце́нта)

Key Takeaways

In the nominative: 1 → nominative singular (agreeing); 2–4 → genitive singular; 5–20 → genitive plural.
For compounds, only the last digit matters: 21→like 1, 22–24→like 2–4, 25–30→like 5+ — repeating every ten.
11–14 are an exception: always genitive plural, no matter that they end in 1–4. The last-digit shortcut starts at 21.
The "genitive after the number" rule is nominative/accusative only. In other cases, the numeral and the (plural) noun both decline: о трёх кни́гах, пяти́ студе́нтам.
полтора́ / полторы́ take genitive singular (like 2–4); fractions and decimals take genitive singular (две це́лых пять деся́тых проце́нта).
Drill the reflex: два рубля́ / пять рубле́й — gen sg vs gen pl. It's the most-used case interaction in Russian.

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