Declension of Cardinal Numbers

Here is the fact that catches every English speaker off guard: in Czech, the numbers themselves decline. Two, three, five are not frozen labels — they are words with case endings, and when the counted phrase lands in the genitive, dative, or instrumental, the number bends to match. English keeps "five" identical in "five crowns," "without five crowns," and "with five crowns." Czech does not: pět korun, bez pěti korun, s pěti korunami. This page gives you the four little paradigms you need — jeden, dva/dvě, tři/čtyři, and the uniform pattern from pět up — and shows them working in real phrases.

Why this matters: numbers agree in oblique cases

In the nominative and accusative — when the counted phrase is the subject or direct object — the number sits in its base form and the noun does the special things you learned elsewhere (dvě koruny, pět korun; see Numbers 0–4 and 5 and up). But the moment a preposition or another case takes over the whole phrase — bez…, ke…, se…, o… — that frozen system melts. Now the number inflects for the case, and the noun simply follows it into the same case.

jeden — declines like ten

jeden ("one") is really an adjective-like word and follows the demonstrative ten ("that") almost exactly. It agrees with its noun in gender, number, and case.

Masculine accusative is *jeden for inanimate nouns, jednoho for animate ones.

dva / dvě — two oblique forms only

dva (masculine) / dvě (feminine and neuter) has just two oblique forms, and they cover all the cases between them: dvou for genitive and locative, dvěma for dative and instrumental.

tři and čtyři — their own endings

tři ("three") and čtyři ("four") share one pattern but spell it slightly differently. Learn them as a pair.

From pět up: one form for everything

Here the system finally turns easy. From pět ("five") onward, each number has a single oblique form ending in -i, and that one form does duty for the genitive, dative, locative, and instrumental alike. You learn one ending and stop worrying about which case you are in.

The round hundred and thousand behave like nouns instead (sto declines like the neuter město, tisíc like the masculine stroj); they get their own page, Hundreds, Thousands, Millions.

How this differs from English

English numbers are completely inert: "two," "three," "five" never change shape, and the preposition carries all the grammatical work — "with two friends," "after three years," "about five students." Czech splits that work between the preposition and the number: the preposition selects the case, and then the number takes a case ending to show it. To an English speaker this feels like the number is being conjugated, and in a sense it is. The instinct to leave the numeral bare — se dva kamarády instead of se dvěma kamarády — is the single most common A2 error with numbers, because it imports the English "numbers don't change" rule wholesale. They do change. Train the four oblique forms — dvou/dvěma, tří/čtyř, pěti — until they come automatically after a preposition.

Common Mistakes

Key Takeaways

• Czech cardinal numbers decline: in oblique cases the number itself takes an ending, and the noun follows it.
• jeden bends like ten, agreeing in gender/number/case (jednoho, jednomu, jedním, jedné, jednu).
• dva/dvě has two oblique forms: dvou (gen./loc.) and dvěma (dat./ins.).
• tři → tří, třem, třech, třemi; čtyři → čtyř, čtyřem, čtyřech, čtyřmi.
• From pět up, one -i form covers every oblique case: pěti, šesti, deseti, dvaceti.
• The error to kill: leaving the numeral bare after a preposition (se dva → se dvěma).