In short

English numerals never change shape: “with twenty-five books” uses the very same “twenty-five” as “twenty-five books”. Ukrainian numerals, by contrast, decline through all six cases, and they do so in several different patterns depending on their size. This lesson sorts the higher cardinals (5–100) into their patterns, shows how a compound (multi-word) numeral makes every part inflect, and adds the collective numerals (дво́є, тро́є, че́тверо…) that Ukrainian uses for groups of people and paired objects. So “with twenty-five books” becomes з двадцятьма́ п’ятьма́ книжка́ми - two inflected words, each carrying the instrumental.

The rule

Sort the cardinals 5–100 into four groups; each group inflects predictably.

Group 1 - 5 to 20 and 30 (п’ять … двадцять, тридцять). These behave like a soft-stem noun. Nominative and accusative are identical (п’ять); the genitive, dative and locative share one oblique form ending in -и́ (п’яти́, шести́, десяти́); the instrumental has two equally standard endings, -ьма́ and -ьома́ (п’ятьма́ / п’ятьома́). When the numeral refers to people it usually switches to the “animate” forms in -ох / -ом (п’ятьо́х, п’ятьо́м), which are also compulsory for collective numerals (below).

Group 2 - 50, 60, 70, 80 (п’ятдеся́т … вісімдеся́т). Only the second half declines, exactly like де́сять in Group 1; the first element п’ят-/шіст-/сім-/вісім- is frozen: п’ятдеся́т → п’ятдесяти́ → п’ятдесятьма́. There is no linking vowel inside the word (the form is п’ятдесяти́, not the Russian-style пятидесяти).

Group 3 - 40, 90, 100 (со́рок, дев’яно́сто, сто). Each has only two forms: the nominative/accusative, and a single oblique form covering genitive, dative, instrumental and locative - сорока́, дев’яно́ста, ста. (Note the end stress: сорока́ the numeral versus соро́ка “magpie”.)

Compound numerals (складені) are written as several separate words (два́дцять п’ять, сімдеся́т три). The rule is simple and unforgiving: decline every word by its own group’s pattern. English changes nothing; Ukrainian changes everything.

Collective numerals (збірні) - дво́є, тро́є, че́тверо, п’я́теро, ше́стеро, се́меро, во́сьмеро, де́в’ятеро, де́сятеро (and оби́два/оби́дві, обо́є) - denote a set taken as a whole. They combine with: masculine personal nouns (тро́є хло́пців), the young of animals (дво́є кошеня́т), plural-only nouns (че́тверо двере́й, дво́є окуля́рів), substantivised adjectives (дво́є військо́вих), and personal pronouns (нас було́ тро́є). They are not used with feminine persons or with things counted one by one - there you keep the ordinary cardinal (дві сестри́, not дво́є сесте́р). In the oblique cases дво́є/тро́є borrow the forms of два/три (двох, двом, двома́), while че́тверо and up borrow the animate -ох/-ом forms of their cardinal (чотирьо́х, п’ятьо́х); оби́два/оби́дві/обо́є follow neither route - their obliques come from the stem обо- (below). Whatever case the numeral takes, its noun goes into the same case in the plural - see Numeral–noun agreement (case government).

Forms & patterns

Group 1 - 5–20, 30 (20 and 30 follow п’ять exactly; the teens take the same endings but keep the stress fixed on -на́дцять: одина́дцяти, чотирна́дцятьма):

Animate (“people”) variant, all of Group 1: Р. п’ятьо́х, Д. п’ятьо́м, М. (на) п’ятьо́х.

Group 2 - 50–80 (only -десят moves; the first element is frozen):

Group 3 - 40, 90, 100 (one oblique form each):

Compound numerals - every word declines (25 = Group 1 + Group 1; 73 = Group 2 + три):

Collective numerals (дво́є/тро́є take the forms of два/три; че́тверо+ take the -ох/-ом forms):

The rest of the series inflects like че́тверо / п’я́теро: ше́стеро → шістьо́х, се́меро → сімо́х, во́сьмеро → вісьмо́х, де́в’ятеро → дев’ятьо́х, де́сятеро → десятьо́х.

Оби́два (m./n.), оби́дві (f.) and обо́є (a mixed pair) - “both” - split by gender only in Н./З. Every oblique is built on the stem обо-: Р. обо́х, Д. обо́м, animate З. обо́х, О. обома́, М. (на) обо́х - never by declining the -два half (обидво́х, обидвома́).

Examples

Common mistakes

• з п’ять дру́зями -> з п’ятьма́ дру́зями - a numeral before its noun must take the same case (here instrumental), not stay in the nominative.
• з двадцять п’ятьма́ студе́нтами -> з двадцятьма́ п’ятьма́ студе́нтами - in a compound numeral every word declines, not only the last one.
• п’ятидесяти́ гри́вень -> п’ятдесяти́ гри́вень - in 50–80 the case sits on «-десят» and the first element never changes, so there is no linking «-и-» inside the word (that «-и-» is the Russian pattern).
• до сорок ро́ків -> до сорока́ ро́ків - 40, 90 and 100 have one oblique form each (сорока́, дев’яно́ста, ста) covering the genitive, dative, instrumental and locative.
• п’я́теро жіно́к -> п’ять жіно́к - collective numerals count men, young creatures and plural-only nouns, so a feminine person takes the plain cardinal.
• дво́є до́чок -> дві до́чки - same reason: with a feminine noun use два/дві, not the collective дво́є.

Tips

• Learn the four buckets, not fifty words: 5–20 & 30 follow п’ять; 50/60/70/80 move only their second half; 40/90/100 have a single oblique form each; hundreds you meet later.
• The instrumental of Group 1 has two correct endings, -ьма́ and -ьома́ (п’ятьма́ / п’ятьома́). Pick one and stay consistent within a text.
• For compound numerals, decline word by word - if you can inflect п’ять and двадцять separately, you can inflect двадцять п’ять.
• With people, prefer the animate -ох/-ом forms (п’ятьо́х студе́нтів, допомі́г шістьо́м); the bookish п’яти́/шести́ sound flat for humans and are impossible for collectives.
• Remember the stress trap: сорока́ (the numeral, end-stressed) versus соро́ка “magpie”.
• Reach for a collective numeral (дво́є, тро́є, че́тверо…) for groups of men, baby animals, paired/plural-only nouns and the «нас/вас/їх було…» pattern - never for women or single-counted things.
• After an oblique numeral, put the noun in the same case in the plural: двом студе́нтам, з трьома́ книжка́ми, на сорока́ сторі́нках.