Russian declension

In Russian grammar, the system of declension is elaborate and complex. Nouns, pronouns, adjectives, demonstratives, most numerals and other particles are declined for two grammatical numbers (singular and plural) and six grammatical cases ; some of these parts of speech in the singular are also declined by three grammatical genders (masculine, feminine and neuter). This gives many spelling combinations for most of the words, which is needed for grammatical agreement within and (often) outside the proposition. Also, there are several paradigms for each declension with numerous irregular forms.

Russian has retained more declensions than many other modern Indo-European languages (English, for example, has almost no declensions remaining in the language).

Nouns
Nominal declension is subject to six cases – nominative, accusative, genitive, prepositional, dative, instrumental – in two numbers (singular and plural), and absolutely obeying grammatical gender (masculine, feminine, and neuter). Up to ten additional cases are identified in linguistics textbooks,  although all of them are either incomplete (do not apply to all nouns) or degenerate (appear identical to one of the six simple cases). The most recognized additional cases are locative (в лесу́, на мосту́, в крови́ — in the forest, on the bridge, in (the) blood), partitive (ча́ю, са́хару, коньяку́ — (some) tea, sugar, cognac), and several forms of vocative (Го́споди, Бо́же, о́тче — (O) Lord, God, father). The adjectives, pronouns, and the first two cardinal numbers further vary by gender. Old Russian also had a third number, the dual, but it has been lost except for its use in the nominative and accusative cases with the numbers two, three and four (e.g. два стула, "two chairs", now reanalyzed as genitive singular).

Russian noun cases often replace the usage of prepositions in other Indo-European languages. Their usage can be summarised as:
 * Nominative – the “subject” case
 * Accusative – the “direct object” case
 * Genitive – corresponding to the possessive case or “of + (noun)”
 * Prepositional – used with certain prepositions, such as “in”, “on” etc.
 * Dative – corresponding to “to + (noun)" or the indirect object
 * Instrumental – denoting an instrument used in an action

There are no articles, neither definite nor indefinite (such as the, a, an in English), in the Russian language. The sense of a noun is determined from the context in which it appears. That said, there are some means of expressing whether a noun is definite or indefinite. They are:
 * The use of a direct object in the genitive instead of the accusative in negation signifies that the noun is indefinite, compare: "Я не ви́жу кни́ги" ("I don't see a book" or "I don't see any books") and "Я не ви́жу кни́гу" ("I don't see the book").
 * The use of the numeral one sometimes signifies that the noun is indefinite, e.g.: "Почему́ ты так до́лго?" – "Да так, встре́тил одного́ дру́га, пришло́сь поговори́ть" ("Why did it take you so long?" – "Well, I met one [=a] friend and had to talk").
 * Word order may also be used for this purpose, compare "В ко́мнату вбежа́л ма́льчик" ("Into the room rushed a boy") and "Ма́льчик вбежа́л в ко́мнату" ("The boy rushed into the room").
 * The plural form may signify indefiniteness: "Вы мо́жете купи́ть э́то в магази́нах" ("You can buy this in shops") vs. "Вы мо́жете купи́ть э́то в магази́не" ("You can buy this in the shop").

The category of animacy is relevant in Russian nominal and adjectival declension. Specifically, the accusative has two possible forms in many paradigms, depending on the animacy of the referent. For animate referents (sentient species, some animals, professions and occupations), the accusative form is generally identical to the genitive form (genitive-accusative syncretism). For inanimate referents (simple lifeforms, objects, states, notions), the accusative form is identical to the nominative form (nominative-accusative syncretism). This principle is relevant for masculine singular nouns of the second declension (see below) and adjectives, and for all plural paradigms (with no gender distinction). In the tables below, this behavior is indicated by the abbreviation N or G in the row corresponding to the accusative case.

In Russian there are three declensions:
 * The first declension is used for feminine nouns ending with -а/-я and some masculine nouns having the same form as those of feminine gender, such as "papa" or  "uncle"; also there are common-gender nouns like  "teaser" which are masculine or feminine depending on the person they refer to.
 * The second declension is used for most masculine and neuter nouns.
 * The third declension is used for feminine nouns ending in ь.

There is also a group of several irregular "different-declension nouns" (разносклоня́емые существи́тельные), consisting of a few neuter nouns ending in -мя (e.g. "time") and one masculine noun  "way". However, these nouns and their forms have sufficient similarity with feminine third declension nouns that some scholars such as Litnevskaya consider them to be non-feminine forms of this declension, as written in the tables below.

Nouns ending with -ий, -ия, -ие (not to be confused with substantivated adjectives) are written with -ии instead of -ие in Prepositional: тече́ние – в ни́жнем тече́нии реки́ "streaming – in lower streaming of a river". (As none of these endings are ever stressed, due to vowel reduction the pronunciation difference between -ие and -ии may be hardly noticeable in fluent speech.) But if the words and  are representing compound prepositions meaning "while, during the time of", they are written with -е: в тече́ние ча́са "in the course of an hour". For nouns ending in -ья, -ье, or -ьё, using -ьи in the Prepositional (where endings of some of them are stressed) is usually erroneous, but in poetic speech it may be acceptable (as we replace -ии with -ьи for metric or rhyming purposes): Весь день она́ лежа́ла в забытьи́ (F. Tyutchev).

First declension
The first declension group belongs to nouns with the ending -а and -я. These nouns are typically feminine, but include masculine nouns that have a feminine ending as well.


 * 1) After a sibilant (ж, ч, ш, щ) or a velar (г, к, or х) consonant, и is written.
 * 2) After a sibilant, о is written when stressed; е when unstressed.
 * 3) After a soft consonant, ё is written when stressed; е when unstressed.

Examples: рабо́та – a work/job, ба́ня – a bathhouse, кни́га – a book, ли́ния – a line

Note: In the instrumental case, -ою and -ею instead of -ой and -ей endings may be encountered in the singular.

Second declension – masculine nouns
Nouns ending in a consonant are marked in the following table with – (thus no ending).

Notes:
 * 1) After a sibilant (ж, ч, ш, щ) or a velar (г, к, or х) consonant, и is written, or, for some words, а (глаз — глаза, доктор — доктора, etc.).
 * 2) After a sibilant, ей is written.
 * 3) After a soft consonant, ё is written when stressed; е when unstressed.
 * 4) After a sibilant, о is written when stressed; е when unstressed.

Examples: фильм – a film/movie, писа́тель – a writer, геро́й – a hero, коммента́рий – a comment

Second declension – neuter nouns
Nouns ending in -о and -е are neuter.


 * 1) After a sibilant, о is written when stressed; е when unstressed.
 * 2) After a soft consonant, ё is written when stressed; е when unstressed.
 * 3) For nouns ending in ие in the nominative singular, и is written (but е when stressed — for the word остриё).
 * 4) After a consonant use ей otherwise use й.
 * 5) Also: some masculine nouns ending in -о in the nominative singular (доми́шко, diminutive from дом 'house'); there is only one masculine noun ending in -е in this declension: подмасте́рье.

Examples ме́сто – a place, мо́ре – a sea, зда́ние – a building

Third declension
The third declension is for predominantly feminine nouns, or with a non-standard termination as shown with exceptional words: дитя ('child', archaic) and путь ('path').


 * 1) After a sibilant, а is written.

Examples: кость (f) – a bone, мышь (f) – a mouse, и́мя (n) – a name

Irregular plural forms
There are various kinds of irregularities in forming plurals. Some words have an irregular plural form, but a few use suppletion, being substituted by a different root altogether. Historically, some of these irregularities come from older declensional patterns that have become mostly obsolete in modern Russian.


 * 1) If the word лист has the lexical meaning "paper", then its declension is normal (лист → листы). If it has lexical meaning "leaf (of a tree)", its declension is лист → листья.

Undeclined nouns
Some nouns (such as borrowings from other languages, abbreviations, etc.) are not modified when they change number and case. This appears mostly when their gender appears to have no ending in any declension which suits the final part of the word: these are masculine names on vowels different from -а/-я, female names on hard consonants (names like Триш "Trish" won't take the soft sign to go into third declension like native мышь "mouse"). Most borrowed words ending in Russian in э/е, и, о, у and stressed а are not declined: кафе, пальто (paletot), Дюма etc. Most abbreviations are undeclined (one exception is ). Many people also think that Georgian surnames on -ия like Данелия (დანელია) shouldn't be declined since they are originally something like Russian possessive genitives.

Personal names
Traditionally, a full Russian name consists of a person name (и́мя – given name or first name), patronym (о́тчество – father's name as middle name) and a family name (фами́лия – surname or last name). All of these words have the same grammatical gender as biological one. Slavic, as well as Greek, Roman, Jewish and other person names of European or Semitic origin loaned centuries ago, have gender-specific versions of respective patronyms. To produce a patronym, suffixes -вич- and -вн- are used with final vowel addition or modification: -о for hard consonant (Петро́вич/Петро́вна ⇐ son/daughter of Пётр), -ье for -ий (Григо́рьевич/Григо́рьевна ⇐ Григо́рий), and -е for other cases (Матве́евич/Матве́евна ⇐ Матве́й, И́горевич/И́горевна ⇐ И́горь). Some person names also have versions for both males and females (Алекса́ндр – Алекса́ндра, Евге́ний – Евге́ния).

Additionally, Slavic names have short forms, usually meant for affectionate calls (Ива́н – Ва́ня, А́нна – А́ня; equivalent of Johnny, Annie, etc.). Short forms by themselves can form "reemerging" vocative case (sometimes called neo-vocative); it is used for calling a familiar person, substituting nominative singular by removing last vowel (Артём – Тёма – Тём, О́льга – О́ля – Оль). For this reason, neo-vocative is not possible for male names that can't produce short forms with a final vowel (including some popular ones: Влади́мир, Вита́лий, И́горь). Likewise, there is a neo-vocative form for close relatives: мать – ма́ма – мам (mother – mommy – mom), оте́ц – па́па – пап (father – daddy – dad). When replacing nominative plural (used for always plural nouns), it can be used for collective calls: ребя́та ("guys, lads") – ребя́т, девча́та ("gals") – девча́т.

Most family names in Russia are also gender-specific (shown below in male/female pairs) and declinable like most words (including plural form to denote a married couple or a whole family, as "The Smiths"). They can be divided in these categories (sorted by occurrence):
 * Russian origin, gender-specific, declinable as nouns: -о́в/-о́ва (unstressed for names four of more syllables long), -ев/-ева, -ёв/ёва, -и́н/-ина́ (sometimes stressed for names two syllables long);
 * Russian origin, gender-agnostic, indeclinable: -ы́х, -и́х;
 * Ukrainian origin, gender-specific, declinable as adjectives: -ый/-ая, -о́й/-а́я;
 * Ukrainian or Belarusian origin, gender-agnostic, indeclinable: -е́нко (mostly stressed), -ко́;
 * Ukrainian or Belarusian origin, gender-agnostic, declinable as masculine nouns for males and indeclinable for females: -у́к, -ю́к, -и́к, -е́ц, etc.;
 * Other Slavic origin, gender-specific, declinable as adjectives: -ский/-ская, -цкий/-цкая;
 * Other Slavic or non-Slavic origin, gender-agnostic, declinable as masculine nouns for males and indeclinable for females: -о́вич, -е́вич, -ер, -ман, -берг, etc.

Examples: Here male name is composed of 2nd declension nouns, but there are exceptional endings for Instrumental (patronym: -ем, not -ом; family name: -ым, not -ом). Female name is in 1st declension, but ending -ой is used for a family name in all oblique cases. Plural follows adjectival declension, except that Nominative is short -ы.

Adjectives
A Russian adjective (и́мя прилага́тельное) is usually placed before the noun it qualifies, and it agrees with the noun in case, gender, and number. With the exception of a few invariant forms borrowed from other languages, such as беж 'beige' or ха́ки 'khaki', most adjectives follow one of a small number of regular declension patterns, except for some which provide difficulty in forming the short form. In modern Russian, the short form appears only in the nominative and is used when the adjective is in a predicative role; formerly (as in the bylinas) short adjectives appeared in all other forms and roles, which are not used in modern language, but are nonetheless understandable to Russian speakers as they are declined exactly like nouns of the corresponding gender.

Adjectives may be divided into three general groups:
 * Qualitative (ка́чественные) — denote quality of the object; only adjectives in this group generally have degrees of comparison.
 * Relational (относи́тельные) — denote some sort of relationship; unlikely to act as a predicate or have a short form.
 * Possessive (притяжа́тельные) — denote belonging to a specific subject; have some declensional peculiarities.

Adjectival declension
The pattern described below matches the full forms of most adjectives, except possessive ones; it is also used for substantivated adjectives as and for adjectival participles.


 * 1) After a sibilant or velar consonant, и, instead of ы, is written.
 * 2) When a masculine adjective ends in -ой, the -ой is stressed.
 * 3) After a sibilant consonant, neuter adjectives end in ее. This is sometimes called the хорошее rule.
 * 4) Accusative in the masculine singular, and in the plural for all genders, depends on animacy, as for nouns.
 * 5) Instrumental feminine ending -ой/ей for all adjectives has alternative form -ою/ею, which differs only stylistically from the standard form.

Russian differentiates between hard-stem (as above) and soft-stem adjectives. Note the following:
 * Masculine adjectives ending in the nominative in ий and neuters in ее are declined as follows: его (read: ево), ему, им, and ем.
 * Feminine adjectives in яя are declined ей and юю.
 * Plural adjectives in ие are declined их, им, ими and их.
 * Case endings -ого/-его are to be read as -ово/ево.

Examples:

Before 1917, adjectival declension looked quite different, at least in writing; for example, there were special feminine plural forms, as in French. In modern editions of classical poetry some elements of this system are still used if they are important for rhyme or metrics. A notable example is ending -ыя (bisyllabic) instead of -ой (monosyllabic) for genitive single female adjectives, which were considered bookish and deprecated even in the times of Alexander Pushkin but were still used by him in lines such as «тайна брачныя постели» («Евгений Онегин», IV, L).

Comparison of adjectives
Comparison forms are usual only for qualitative adjectives and adverbs. Comparative and superlative synthetic forms are not part of the paradigm of original adjectives but are different lexical items, since not all qualitative adjectives have them. A few adjectives have irregular forms that are declined like ordinary adjectives: большо́й 'big' — бо́льший 'bigger', хоро́ший 'good' — лу́чший 'better'. Most synthetically derived comparative forms are derived by adding -ее or -ей to the adjective stem: кра́сный 'red' — красне́е 'more red'; distinguishing such adjectives from the comparative adverbs whose forms they share is at best difficult, if not impossible. Superlative synthetic forms are derived by adding suffix -ейш- or -айш- and additionally sometimes prefix наи-, or using a special comparative form with наи-: до́брый 'kind' — добре́йший 'the kindest', большо́й 'big' — наибо́льший 'the biggest'.

Another method of indicating comparison uses analytical forms with adverbs бо́лее 'more' / ме́нее 'less' and са́мый 'most' / наибо́лее 'most' / наиме́нее 'least': до́брый 'kind' — бо́лее до́брый 'kinder' — са́мый до́брый 'the kindest'. This pattern is rarely used if special comparative forms exist.

Possessive adjectives
Possessive adjectives are used in Russian to a lesser extent than in most other Slavic languages, but are still in use. They answer the questions чей? чья? чьё? чьи? (whose?) and denote only animated possessors. Alternative for possessive adjectives are possessive genitives which are used much more commonly. There are three suffixes to form them: -ов/ев, -ын/ин and -ий.

Suffix -ов/ев is used to form adjective from a word denoting single human which is masculine and ends on consonant; selection depends on if the stem hard or soft. Suffix -ын/ин is similar but is attached to feminine words or masculine ending in -а/я. Both types are more common in spoken language than in literary (though being acceptable in both styles) and generally are forms of kinship terms, given names and their diminutives: ма́ма — ма́мин 'mom's', оте́ц — отцо́в 'father's', Са́ша — Са́шин 'Sasha's' /for diminutives from both Alexandr and Alexandra/. Words of this type also are common as Russian surnames, like Пушкин (derived from 'gun' which used to be a nickname).

Adjectives on -ов and -ин are declined via mixed declension: some of their forms are nominal, some are adjectival, and some are ambivalent.

Adjectives on -ий (speaking about suffix, not case ending; before vowels, this suffix deceases to single sound and is written as ь) are used for deriving adjectives mostly from animal species (in Old East Slavic, this suffix derived possessive adjectives from plural possessors ): лиса 'fox' — лисий 'of a fox', 'likely for a fox'. Declension of such adjectives is nominal in nominative and accusative (except masculine and plural animated accusative) and adjectival for other forms.

There exist many stable expressions which include possessive adjectives following either of the two declensions shown above: но́ев ковче́г (Noah's ark, from Ной "Noah"), эвкли́дова геоме́трия (Euclidean geometry, from Эвкли́д "Euclides"), ма́рсово по́ле (the Field of Mars), а́вгиевы коню́шни (the Augean stables, from А́вгий "Augeas"), во́лчий аппети́т (a wolfish appetite, from волк "wolf"), крокоди́ловы слёзы (crocodile tears, from крокоди́л "crocodile"), ка́ждый бо́жий день (every God-given day, from Бог "God"), etc. Notice how the latter two differ from the general rule: крокоди́лов has ending as if a crocodile were a male human, and бо́жий has  ending as if God is treated as an animal or (in Old Russian) a crowd (perhaps, symbolizing Holy Trinity).

Personal pronouns

 * Russian is subject to T-V distinction. The respectful form of the singular you is the same as the plural form. It begins with a capital letter: Вы, Вас, Вам etc. in following situations: personal letters and official papers (addressee is definite), and questionnaires (addressee is indefinite), otherwise it begins with minuscule. Compare the distinction between du and Sie in German or tu and vous in French.
 * When a preposition is used directly before a 3rd-person pronoun in oblique cases, н- is prefixed: у него (read: у нево), с неё, etc. Because the prepositional case always occurs after a preposition, the third person prepositional always starts with an н-.
 * Like adjectives and numerals, letter г (g) in genitive and accusative form is pronounced as в (v) его/него ево/нево.

Possessive adjectives and pronouns
Unlike English, Russian uses the same form for a possessive adjective and the corresponding possessive pronoun. In Russian grammar they are called possessive pronouns притяжа́тельные местоиме́ния (compare with possessive adjectives like Peter's = пе́тин above). The following rules apply:
 * Possessive pronouns agree with possessed noun in case, gender, and number: Где мои́ очки́? (plural) "Where are my glasses?"; Ви́дел ли ты мою́ дочь? (feminine accusative) Have you seen my daughter?, even if her father is talking. As in English, they also depend on the person and number of the possessor.
 * The reflexive pronoun свой is used when the possessor is the subject of the clause, whatever the person, gender, and number of that subject.
 * In literary Russian non-reflexive pronouns are not used for the 3rd person; the genitive of the personal pronoun is used instead: его́ (masc./neut. sing. possessor), её (fem. sing. possessor) and их (pl. possessor). Unlike other genitives used with a possessive meaning, in modern Russian these words are usually placed before the object of possession. In colloquial speech, however, sometimes "adjectived" forms are used: его́нный (masc./neut. sing. possessor, rare), и́хний (pl. possessor); they are declined as adjectives.
 * Example of the difference between reflexive and non-reflexive pronouns:
 * “Он лю́бит свою́ жену́ = He loves his (own) wife”;
 * “Он лю́бит его́ жену́ = He loves his (someone else's) wife” (for literary Russian);
 * “Он лю́бит его́ = He loves him/it”.
 * Unlike Latin where a similar rule applies for the 3rd person only, Russian accepts using reflexives for all persons:
 * “Я люблю́ свою́ жену́ = I love my wife”;
 * “Я люблю́ себя́ = I love myself”.
 * The ending -его is pronounced as -ево.

Interrogative pronouns

 * The ending -его is pronounced as -ево.

Numerals
Russian has several main classes of numerals (числи́тельные): cardinal, ordinal, collective, and fractional constructions. It also has other types of words, relative to numbers: Here are the numerals from 0 to 10:
 * multiplicative adjectives and compound nouns: еди́нственный – single (sole, unique), двойно́й – double, учетверённый – quadrupled, трёхкра́тный – three-times (also as repetition adjective), пятицили́ндровый – five-cylinder; однообра́зие – monotony, тро́йственность – triplicity, семибо́рье – heptathlon;
 * multiplicative verbs: утро́ить/утра́ивать – triple, уполови́ни(ва)ть – halve (imp./perf. with/without -ва- suffix);
 * multiplicative adverbs: вдвойне́ – doubly, впя́теро – five times (for compound adverbs: впя́теро быстре́е – 5 times faster), вполови́ну – half as;
 * collective and repetition adverbs: втроём – three together; четы́режды – four times (with a verb for repeated action or a noun for repeatedly acquired state or title);
 * two interrogative and negative adverbs: ско́лько? – how much/many?; ниско́лько – none (at all);
 * counting-system, ordinal and partitive adjectives: двои́чный – binary, шестнадцатири́чный – hexadecimal; перви́чный – primary; тро́йственный (трёхча́стный) – three-sided (tripartite);
 * two dual numerals: о́ба – both (masculine/neuter), о́бе – both (feminine); but no single word for "neither";
 * numeric-pronominal, indefinite quantity words: ско́лько-то, ско́лько-нибудь – some, as much; не́сколько – few; (не)мно́го – (not) much/many; (не)ма́ло – (not a) little; много and мало are also used for compound words: малозна́чимость – small significance, многоу́ровневый – multilevel, малопоня́тно – vaguely (lit.: little clear);
 * nouns for a number itself or an object defined by it (symbol, playing cards, banknote, transport route, etc.): едини́ца – number "1", unit; пятисо́тка – number "500" (all feminine); noun for masculine ноль (zero) is но́лик.
 * multiple loaned numerals (also used as prefixes and first roots for compound words) from Greek, Latin and (for musical terminology) Italian;



Declension of cardinal numerals
Different Russian numerals have very different types of declension. The word оди́н (one) is declined by number, gender (in the singular), and case. The word два (two) is declined by gender and case, all other numbers have only case to decline by. The words for 50, 60, 70, 80, 200, 300, 400, 500, 600, 700, 800, 900 are unique for Russian, as they decline not only with ending in their end, but also with part of word in their middle (since they are originally composed from two words): Nom. пятьдеся́т (50) – Gen. пяти́десяти etc. (compare пять деся́тков – пяти́ деся́тков "five tens").

Compound number phrases are created without any unions: сто пятьдеся́т три ры́бы "153 fish". All numerals are declined concurrently, albeit not always in the spoken language. If numeral is in Nominative or Accusative, ending of the noun is defined by the last numeral word (the least order, see examples below), but this may not be true for an adjective attached to this noun.

Most numbers ending with "1" (in any gender: оди́н, одна́, одно́) require Nominative singular for a noun: два́дцать одна́ маши́на (21 cars), сто пятьдеся́т оди́н челове́к (151 people). Most numbers ending with "2", "3", "4" (два/две, три, четы́ре) require Genitive singular: три соба́ки (3 dogs), со́рок два окна́ (42 windows). All other numbers (including 0 and those ending with it) require Genitive plural: пять я́блок (5 apples), де́сять рубле́й (10 rubles). Genitive plural is also used for numbers ending with 11 to 14 and with inexact numerals: сто оди́ннадцать ме́тров (111 meters); мно́го домо́в (many houses). Nominative plural is used only without numerals: э́ти дома́ (these houses); cf. три до́ма (3 houses; G. sg.). These rules apply only for integer numbers. For rational numbers see below.

In oblique cases, noun and number take both this case, except that the numbers ending with "thousand", "million", "billion" etc. (nouns: ты́сяча (f.), миллио́н (m.), миллиа́рд (m.)) in singular or in plural are regarded as nouns and always require Genitive case in plural: пятью́ ты́сячами (Instr.) маши́н (Gen.); cf. пятью́ маши́нами and пятью́ ты́сячами тремяста́ми маши́нами (all Instr.). Initial (leftmost) numeral "1" can be omitted in combinations (одна́) ты́сяча (ты́сяча и одна́ ночь – 1001 nights), (оди́н) миллио́н, etc.

Nouns со́тня ("approximately 100", f.) and па́ра ("pair", f.) can be declined and can form compound numerals: три со́тни (≈300), пять пар носко́в (5 pair of socks). Approximate numbers are colloquially formed by reversing word order, exchanging numeral and noun: мину́ты три (≈3 minutes). Ranges (hyphenated) are also possible: пять-шесть дней (5–6 days), дней пять-шесть (probably 5–6 days). The word ми́нус (minus) declines if standalone, but does not for negative numbers: минус три гра́дуса – minus three degrees (wrong: *минуса три градуса); however: три минуса – three minuses.

Dative, Instrumental and Prepositional cases for "zero" more often use нул- root instead of нол-. The numbers from 11 to 19 are: оди́ннадцать, двена́дцать, трина́дцать, четы́рнадцать, пятна́дцать, шестна́дцать, семна́дцать, восемна́дцать, девятна́дцать. They decline in the same way as 20 (два́дцать).

For numbers above 1,000 Russian uses a modified short scale with the following loanwords: миллио́н (106, million; as for both long and short scales), миллиа́рд (109, milliard; as for long scale – an exception), триллио́н (1012, trillion), квадриллио́н (1015, quadrillion), квинтиллио́н (1018, quintillion), etc. (continued as short scale). They decline in the same way as миллио́н. Russian uses words биллио́н (billion) and numerals with -ard endings only in historical texts or literal translations. Also, биллиа́рд (billiard) is a noun meaning a cue sport.

Note for superscript case notations: small letters denote singular forms, capitals denote plural. Метр is masculine (important for "51"); both метр and тысяча are inanimate (important for Accusative). Blue digits are indicatives of case endings, marked by blue letters.

Collective numerals
Collective numerals (собира́тельные числи́тельные) are used in Russian (and many other Slavic languages) instead of usual cardinal ones in specific lexical and semantic situations. Russian collective numerals are different from the cardinal numerals in that the former emphasize ‘the totality’ or ‘the aggregate as a whole’, while the latter – ‘the individuated quantity’. Only numerals from 2 to 7  are actively used nowadays, while 8 to 10 are seldom used and 11–13 are not normative; word  (both) is also considered to be collective numeral. In nominative and accusative, they always force the noun into genitive plural form (while their own accusative form is dependent from animacy of the noun): трое друзей на охоту пошли, вижу двоих мужчин, вижу двое саней. (Three friends went hunting [together], I see two men [together], I see two sleighs [together].) These numerals are seldom used in oblique cases, especially instrumental. A brief table of usage situations follows:

Dobrushina and Panteleeva (2008), having analyzed usage of два/двое in a Russian corpus, summarize cases of usage of collective numerals in the following common rules:
 * 1) Collective numerals denote number of persons likely to have collective behaviour, i.e., existence in groups, not one by one: боевики́ 'militants', жи́тели 'inhabitants', пассажи́ры 'passengers',  'soldiers'.
 * 2) Collective numbers are used while denoting several persons to emphasize unity, cohesion of this group.
 * 3) Contexts of nominal groups with collective numerals have properties showing their individualization and dedication: referentness, empathy, definiteness; they are unlikely to be out of focus.

Ordinal numerals
Ordinal numbers have grammatically no differences with adjectives. While forming them, upper three orders of numerals are agglutinated to nearest dividing power of 1000, which results in constructing some of the longest natural Russian words, e.g. стапятидесятитрёхты́сячный (153,000-th), while the next is сто пятьдеся́т три ты́сячи пе́рвый (153,001-st). In the latter example, only the last word is declined with noun.

Fractions
Fractions are formed as: (how much parts), expressed by cardinal number in case of the phrase, plus (of how numerous parts), expressed by ordinal number; the construction is formed as like it were related to word "part" (grammatically feminine), which is usually omitted. Noun to such construction always comes in Genitive single, also as like it belonged to word часть: девяно́сто две пятидеся́тых то́нны "92/50 tons". If an integer precedes a fraction, it is bound to it usually with the conjunction, while the noun remains in Genitive: два и три восьмы́х оборо́та "2 3/8 turns" (оборо́т is masculine, so the numeral is два, not *две).

Fractions 1/2, 1/3 and 1/4 have proper names (nouns): полови́на, треть and че́тверть, which are used instead of ordinal numbers. They are also often added with preposition с, while form of noun appears to be related to the integer part rather than to the fraction: де́сять с че́твертью [Instr.] оборо́тов [Gen.] "10 1/4 turns". Prefixes (with Genitive) and полу- (with Nominative) are used for "half" of something: пол-лимо́на (half of a lemon), полчаса́ (half an hour; but: полови́на ча́са); полуме́сяц (half moon, crescent). Words with пол- are not declined, and there is a set of rules for writing with or without dash.

For "1 1/2" there is a special word (feminine полторы́; in oblique cases полу́тора; requires Genitive): полтора́ я́блока – 3/2 apples. It can be used with larger numbers (полторы́ ты́сячи – 1 500, полтора миллио́на – 1 500 000) and, for approximate values, with smaller numbers (полтора деся́тка – ≈15, полторы со́тни – ≈150). There was also now-outdated form for exactly 150. As with other single-word numerals, it's possible to form nouns and multiplicative adjectives, associated with "1.5": полу́торка (old truck with 1.5 tonnes of payload capacity), полтора́шка (1.5 liter plastic bottle for beverage); полу́торный (something of 150% amount). Also (colloquially): полтора́ челове́ка "almost nobody" (lit. one and a half men).

To read decimal fractions, convert them to simple ones: 2,71828 = 2+71828/100000 - два и се́мьдесят одна́ ты́сяча восемьсо́т два́дцать во́семь стоты́сячных. After integer in such cases is often used word це́лая (substantiated adjective "full, integer", which also refers to omitted word часть and thus is feminine): 3,14 – три це́лых (и) четы́рнадцать со́тых (union is often omitted); word це́лая can appear also in naming non-decimal simple fractions: 2 3/8 – две це́лых три восьмы́х. Zero before comma is often read: 0,01 = 0+1/100 – ноль це́лых одна́ со́тая (shortly: одна́ со́тая). Informally, decimal fractional part can be read more conveniently as sequence of simple digits and numbers: два и семь-восемна́дцать-два́дцать во́семь. Same method is used to read long numerals unrelated to a noun (phone numbers, address indexes, etc.), grouping two or three digits: 123406 – сто два́дцать три четы́реста шесть, двенадцать три́дцать четы́ре ноль шесть (forced ноль added to avoid missing digit).

Count form
Russian also has so-called "count form" (счётная фо́рма) for use by nouns in numerical phrases instead of genitive plural (for some words mandatory, for others optional), mainly with units of measure (especially derived from names): во́семь бит (8 bits; not *би́тов), шестна́дцать байт (16 bytes), две́сти два́дцать вольт (220 volts), пять килогра́мм(ов) (5 kilograms; optional). But: коли́чество ба́йтов (amount of bytes), изба́виться от ли́шних килогра́ммов (get rid of excess kilograms).

Count form also exists for paucal numbers (1.5, 2, 3 and 4); usually it coincides with genitive singular, but has notable exceptions with stressed endings: два часа́ (2 hours), but середи́на ча́са (middle of an hour); два́дцать два шара́ (22 balls), but объём ша́ра (volume of the ball); три ряда́ (3 rows/lines), but вы́йти из ря́да (step out of the line); четы́ре шага́ (4 steps), but полша́га (half a step). Полчаса́ (half an hour) is additional exception; other nouns with пол- prefix does not have stressed -а ending.

A few nouns have unrelated suppletive genitive plural forms: 4 го́да, but 5 лет (years); 3 челове́ка, but 30 люде́й/челове́к (people; optional). Count forms for adjectives and nouns with adjectival declension after numerals require genitive plural and nominative plural: два лу́чших (G. pl.) игрока́ (G. sg.) "2 best players"; три зелёные (N. pl.) прямы́е (N. pl.) lit. "3 green straight lines", but три зелёных (G. pl.) прямы́х (G. pl.) штриха́ (G. sg.) lit. "3 green straight strokes".