This is the first part of the lesson. The rest, the exercises and the reviews are in the app.
Ordinal numbers: prvi, drugi, treći
Cardinal numbers answer the question “how many?”: jedan, dva, pet (one, two, five). Ordinal numbers answer “which one in the row?”: first, second, fifth. In Serbian they are called redni brojevi, and one fact makes them much easier than they look: a Serbian ordinal is an adjective. It changes for gender, number and case and agrees with its noun, exactly like nov (new) or dobar (good).
That sets the plan for the lesson. First we build the series, from prvi (first) to stoti (hundredth). Then we check that it declines on the adjective pattern you already know. Then comes the part you will use most: dates. Where English says “on the fifth of May”, Serbian uses no preposition at all: it puts both the number and the month into the genitive, the case whose core meaning is “of”: petog maja. Then come years, floors, school years and centuries.
The series: from prvi to stoti
The row starts with three words you need to know cold, because no simple rule gets you from the cardinal to them: prvi (first), drugi (second), treći (third). English has the same irregular trio: nobody says “oneth” or “twoth”. drugi also means “other”: drugi razred is the second year of school, but drugi čovek is another man. After that, Serbian mostly uses one easy trick: take the cardinal and add the adjective ending -i, much as English adds -th.
Watch the small shifts. četvrti is worth learning on its own: it is not četiri plus -i but a word of its own, short and compact, chet-vr-ti, with the r acting as the vowel of the middle syllable (the lesson “Syllabic r”). sedam → sedmi and osam → osmi: the a of the last syllable drops out as soon as an ending is added. This is the “fleeting a” of dobar → dobra (the lesson “Fleeting a”); English trims its stems too, in five → fifth and twelve → twelfth. And šesti, deveti, deseti are model cases: just the number plus -i. After that the series is mechanical:
The numbers 11–19 end in -naesti (petnaesti, šesnaesti), the round tens in -deseti (trideseti, četrdeseti). And in a compound number, just as in English, only the last word becomes an ordinal. English says “twenty-first”, not “twentieth-first”; Serbian says dvadeset prvi, where dvadeset stays a plain cardinal and only prvi turns ordinal. Keep this in mind; it comes back when the endings start to change.
Cheat sheet
The cheat sheet — everything essential from the lesson on one page. In the app it opens at any time.
Ordinal numbers: prvi, drugi, treći
An ordinal (redni broj) answers “which one in the row?” and is grammatically an adjective, only in the long form in -i: it agrees in gender, number and case and declines like an adjective. The first three are special; after that: cardinal + -i.