Esperanto marks plurality even when an ordinary whole-number cardinal has already made the quantity obvious. Unu libro is singular, but du libroj and cent libroj require -j. That apparent redundancy is useful: the noun visibly remains plural throughout the sentence, and any adjective and accusative marking follow the same regular pattern.
The pieces have separate jobs. The invariant cardinal tells the quantity; the noun ending -o identifies a noun; -j marks plural number; and -n marks the accusative role. In Mi aĉetis tri novajn librojn, the number tri stays unchanged while both novajn and librojn show plural accusative agreement.
For the formation and spelling of the numerals themselves, see cardinal numbers. This page concentrates on the noun phrase that follows them.
Whole-number cardinals: one takes singular; larger counts take plural
With direct whole-number cardinal counts, use a singular count noun after unu and a plural count noun after quantities greater than one.
Sur la breto restas unu libera loko.
There is one free space left on the shelf.
Sur la breto restas du liberaj lokoj.
There are two free spaces left on the shelf.
Ni atendis dudek kvin minutojn, sed la buso ne venis.
We waited twenty-five minutes, but the bus did not come.
The first two examples form the basic contrast: unu loko versus du lokoj. Esperanto does not follow languages in which a noun after a numeral remains in an unmarked singular. If the number says that several countable things are present, -j still appears.
Compound cardinals are written according to the normal number rules, but their internal spelling does not change noun agreement: dudek kvin minutoj, cent tri paĝoj, du mil homoj. Tens and hundreds are joined inside a unit (dudek, tricent), while separate units remain separate (dudek kvin, du mil).
La raporto havas cent tri paĝojn, sed la resumo havas nur du.
The report has 103 pages, but the summary has only two.
Ni ricevis dudek unu aliĝilojn por la kurso.
We received twenty-one registration forms for the course.
Even though dudek unu ends in unu, its total value is greater than one, so aliĝilojn is plural. Agreement follows the complete quantity, not the final word of the numeral.
Edge cases: pli ol unu, zero, and decimals
The whole-number rule should not be stretched into “any mathematical value above one takes plural.” In the established expression pli ol unu (“more than one”), the noun normally remains singular because unu directly precedes and controls it. By contrast, malpli ol du takes a plural noun because du is the controlling cardinal.
Pli ol unu kandidato petis klarigon pri la regulo.
More than one candidate asked for clarification about the rule.
Ni revenos en malpli ol du horoj.
We will return in less than two hours.
With nul and decimal quantities below one, both singular and plural marking are accepted; no single official rule chooses between forms such as nul komo kvin kilogramo and nul komo kvin kilogramoj. Add the usual -n if the measured phrase is a direct object. Ordinary prose usually avoids nul homo(j) and says neniu homo or neniuj homoj instead. For a half unit, duona kilogramo is also a clear alternative.
The number does not take agreement endings
Basic cardinal particles such as unu, du, tri, dek, cent, and mil do not copy the noun's plural or accusative endings. Case and agreement appear on the noun and on any adjective that directly modifies it.
| Role | Esperanto | What changes |
|---|---|---|
| subject, singular | unu nova mesaĝo | no -j or -n |
| subject, plural | tri novaj mesaĝoj | adjective and noun take -j |
| object, singular | unu novan mesaĝon | adjective and noun take -n |
| object, plural | tri novajn mesaĝojn | adjective and noun take -j-n |
Mi ricevis unu gravan mesaĝon ĉi-matene.
I received one important message this morning.
Mi ricevis tri gravajn mesaĝojn ĉi-matene.
I received three important messages this morning.
Ĉu vi mendis du grandajn picojn aŭ tri malgrandajn?
Did you order two large pizzas or three small ones?
In the question, du and tri are unchanged. Grandajn picojn carries plural accusative marking, and malgrandajn keeps that same marking even though the repeated noun picojn is omitted. The syntax, not proximity to the verb, determines -n.
Direct objects after numbers
An entire numbered noun phrase takes the accusative when it is a direct object. The number remains unchanged, but every ordinary adjective and noun in the phrase receives -n.
La teknikisto anstataŭigis kvar difektitajn kablojn.
The technician replaced four damaged cables.
Ni ne trovis la du mankantajn dokumentojn.
We did not find the two missing documents.
Compare a subject with an object:
Tri gastoj alvenis frue; ni salutis la tri gastojn ĉe la pordo.
Three guests arrived early; we greeted the three guests at the door.
The first tri gastoj is the subject, so it has plural -j only. The second is the object, so gastoj becomes gastojn. The determiner la and cardinal tri never change.
Count nouns versus measured substances
A number can directly modify a countable noun: tri pomoj, kvin seĝoj. A substance such as akvo, rizo, or sukero is normally not counted as separate individuals. To quantify it, count a unit or container and link the substance with da.
Bonvolu alporti du botelojn da akvo kaj tri tasojn da kafo.
Please bring two bottles of water and three cups of coffee.
Por la kuko mi bezonas ducent gramojn da faruno.
For the cake I need two hundred grams of flour.
Here botelojn, tasojn, and gramojn are plural accusative count nouns. The substances after da stay unmarked: akvo, kafo, faruno. Do not mechanically turn them into plurals because English conceptualizes several servings. A plural mass noun is possible only with a changed meaning, usually distinct kinds: tri vinoj can mean three wines or wine varieties.
The same pattern distinguishes objects from their contents:
Ni aĉetis ses glasojn kaj du litrojn da suko.
We bought six glasses and two liters of juice.
Ses glasojn counts drinking vessels; du litrojn da suko measures juice. Grammar follows what is being counted.
Mil versus miliono
Mil is a basic cardinal particle, so it directly precedes a plural noun: du mil eŭroj. Miliono, by contrast, is an -o noun. It takes its own plural and accusative endings and normally uses da before what it measures.
La renovigo kostos du mil eŭrojn.
The renovation will cost two thousand euros.
La fonduso kolektis du milionojn da eŭroj.
The fund collected two million euros.
This is a structural difference, not an arbitrary spelling exception. In miliono, the stable numerical root has been made into a noun with -o, so it behaves like other nouns: miliono, milionoj, milionon, milionojn. The smaller basic cardinal mil remains an endingless number word.
A short real-world exchange
— Kiom da biletoj restas? — Nur unu bileto, sed ni bezonas du.
— How many tickets are left? — Only one ticket, but we need two.
The answer can omit the repeated noun after du because the context supplies it. If expressed, it would be du biletojn: plural because there are two, accusative because bezoni takes an object.
Common Mistakes
Leaving the noun singular after a number
❌ Mi rezervis tri ĉambro.
Incorrect: a count noun after tri must be plural.
✅ Mi rezervis tri ĉambrojn.
I reserved three rooms.
Marking the noun but not its adjective
❌ Ŝi aĉetis du ruĝa pomojn.
Incorrect: the adjective must agree in plural and accusative.
✅ Ŝi aĉetis du ruĝajn pomojn.
She bought two red apples.
Adding endings to a basic cardinal
❌ Ni invitis trijn kolegojn.
Incorrect: the basic number tri does not take accusative -n.
✅ Ni invitis tri kolegojn.
We invited three colleagues.
Copying count syntax onto a substance
❌ Mi trinkis du akvojn.
Normally incorrect for an amount of water; the plural suggests two kinds or servings.
✅ Mi trinkis du glasojn da akvo.
I drank two glasses of water.
Treating miliono like mil
❌ La urbo havas du milionoj loĝantojn.
Incorrect: miliono is a noun, takes accusative -n here, and requires da before loĝantoj.
✅ La urbo havas du milionojn da loĝantoj.
The city has two million inhabitants.
Key Takeaways
- With direct whole-number cardinals, use a singular count noun after unu and a plural in -j after larger counts; expressions such as pli ol unu and decimals require separate treatment.
- Basic cardinals do not take plural or accusative agreement endings.
- In an object phrase, adjectives and nouns take -n: tri novajn librojn.
- Count units directly; measure substances with a unit plus da.
- Mil is a basic cardinal, but miliono is a full noun with ordinary noun endings.
Related Topics
- Cardinal NumbersA1 — Use Esperanto cardinal numbers to count, quantify noun phrases, identify items, and read basic dates, times, measurements, and decimal notation.
- Building Large NumbersA1 — Build and use thousands, millions, and larger Esperanto numbers with correct spacing, noun behavior, scale values, and case marking.
- Singular and Plural NounsA1 — How Esperanto builds singular, plural, and accusative noun forms from a stable root using -o, -j, and -n.
- Count and Mass MeaningsA1 — How Esperanto distinguishes countable individuals from unbounded substances and shifts nouns between those meanings.
- Adjective Agreement in the AccusativeA1 — Learn when Esperanto adjectives copy the accusative -n, how -ajn is built, and why predicative adjectives normally remain without -n.
- Distance, Weight, and VolumeB1 — Measure dimensions, separation, weight, and capacity with unit nouns, accusative extent, je and de phrases, and da after quantities.