Esperanto follows an international decimal-comma convention: 3,14 is read tri komo unu kvar. Digits after the comma are read separately, while procento behaves as a count noun and mathematical signs have conventional spoken equivalents such as plus, minus, multiplikite per, and dividite per.
The decimal comma
Use a comma between the whole and fractional parts:
La temperaturo altiĝis de 18,5 ĝis 21,3 gradoj.
The temperature rose from 18.5 to 21.3 degrees.
Read the whole-number part normally, say komo, and then read every following digit separately:
| Written number | Normal reading |
|---|---|
| 0,5 | nul komo kvin |
| 3,14 | tri komo unu kvar |
| 46,987 | kvardek ses komo naŭ ok sep |
| 2,05 | du komo nul kvin |
The zero in 2,05 matters; omitting it would produce 2,5. Do not turn the fractional digits into a cardinal block: 46,987 is not read kvardek ses komo naŭcent okdek sep in the ordinary decimal-reading convention.
La mezurilo montras 0,07 miligramojn.
The meter shows 0.07 milligrams.
Both nul and the noun nulo are established names/readings for zero, but invariant nul is concise and standard in digit strings: nul komo nul sep.
Decimal quantities and noun grammar
The written decimal does not receive Esperanto endings. A following unit written as a word does:
La botelo enhavas 1,5 litrojn da akvo.
The bottle contains 1.5 liters of water.
La pakaĵo pezas 0,8 kilogramojn.
The package weighs 0.8 kilograms.
The unit is normally plural with a nonintegral decimal quantity, including values below one. Its case follows the sentence: litrojn is the direct object of enhavas, while kilogramojn is a measured complement of pezas. In technical notation, 1,5 L and 0,8 kg use invariable symbols instead.
Decimals and fractions can name the same quantity:
Nul komo kvin egalas al unu duono.
Zero point five equals one half.
Choose decimals for measurement and calculation when that format is convenient; use words such as duono and kvarono when the fraction is conceptually important. See fractions.
Grouping large numbers
To make long integers readable, group digits in threes with narrow spaces: 12 345 678. A comma cannot group thousands because it marks the decimal boundary in Esperanto. Periods have historically been used for grouping in some texts, but spaces are the clearest international recommendation.
La datumbazo enhavas 12 345 678 registrojn.
The database contains 12,345,678 records.
This notation keeps 12 345,67 unambiguous: twelve thousand three hundred forty-five and sixty-seven hundredths in decimal notation. In prose, attach a unit or noun so that readers know what the value measures.
Percentages with procento and elcento
Procento literally names one hundredth. It is an ordinary noun: unu procento, du procentoj, dek procentojn where accusative is required. The transparent synonym elcento is also standard and understandable, though procento is more internationally familiar.
Nur unu procento de la aliĝintoj nuligis sian mendon.
Only one percent of those registered canceled their order.
Preskaŭ sesdek procentoj de la dungitoj laboras almenaŭ unu tagon hejme.
Almost sixty percent of the employees work at least one day at home.
Use de to name the whole from which the percentage is calculated. With the symbol, 60% is read sesdek procentoj (or sesdek elcentoj). The symbol is not pronounced procent-signo inside the value.
Case still depends on syntax:
La enketo atingis okdek procentojn de la celita grupo.
The survey reached eighty percent of the target group.
La rabato estas dudek procentoj.
The discount is twenty percent.
In the first sentence, the percentage phrase is the object of atingis and takes -n. In the second, it is a predicate complement after estas and stays nominative.
Change by a percentage
Use je to mark the amount of a rise or fall clearly:
La vendoj kreskis je 8,4 procentoj dum la unua duonjaro.
Sales grew by 8.4 percent during the first half-year.
La prezo ne malaltiĝis je dek procentoj; ĝi malaltiĝis nur je du procentoj.
The price did not fall by ten percent; it fell by only two percent.
After je, the noun stays nominative-form: je 8,4 procentoj, not procentojn. In a close contrast the unit can be omitted when it is completely recoverable, but repeating it is clearer in technical prose.
Distinguish relative percent change from percentage-point change. If support rises from 40% to 50%, the increase is ten procentpunktoj but twenty-five percent relative to the original 40%. In technical or journalistic writing, name procentpunktoj explicitly:
Subteno kreskis de 40% ĝis 50%: je dek procentpunktoj, ne je dek procentoj.
Support rose from 40% to 50%: by ten percentage points, not by ten percent.
This is a mathematical distinction shared across languages, but careless English source text often carries the ambiguity into translation.
Addition, subtraction, and equality
Read + as plus or, in simple addition, kaj. Read − as minus. The equality sign can be estas, faras, or egalas al; faras is foundational, while estas and egalas al are very common today.
Du plus tri estas kvin.
Two plus three is five.
Dudek mil minus tri mil egalas al dek sep mil.
Twenty thousand minus three thousand equals seventeen thousand.
Mathematical strings behave somewhat like quoted formulas; ordinary sentence grammar plays a smaller role inside them. Outside formulas, plus and minus can coordinate added or subtracted amounts, and case should follow the larger sentence:
La kotizo estas kvindek eŭroj plus kvin eŭroj por sendo.
The fee is fifty euros plus five euros for shipping.
Multiplication and division
The clearest general readings are multiplikite per and dividite per:
Dudek du multiplikite per ses egalas al cent tridek du.
Twenty-two multiplied by six equals one hundred thirty-two.
Sep dividite per du estas tri komo kvin.
Seven divided by two is three point five.
An -oble form offers a shorter multiplication reading: kvinoble sep estas tridek kvin. Keep it distinct from kvin fojojn, which counts five occasions in ordinary language.
— Kiom estas dek kvin dividite per tri? — Kvin.
— What is fifteen divided by three? — Five.
Powers, roots, and signed values
Common powers and roots have transparent readings:
| Expression | Esperanto reading |
|---|---|
| 10² | la dua potenco de dek or dek kvadrate |
| 5³ | la tria potenco de kvin or kvin kube |
| √4 | la kvadrata radiko de kvar |
| ∛27 | la kuba radiko de dudek sep |
The systematic potenco/radiko forms are best for unfamiliar exponents. Kvadrate and kube are concise conventional alternatives.
For signed values, say plus kvin and minus kvin. In weather reports, kvin gradoj sub nulo is often more conversational than minus kvin gradoj:
Nokte la temperaturo falos ĝis minus ses gradoj.
At night the temperature will fall to minus six degrees.
Do not confuse mathematical minus with the word-forming prefix mal-. Minus kvin is −5; malkvin is not a standard number.
Common Mistakes
Copying the English decimal point
❌ La rezulto estas 3.14.
Incorrect Esperanto decimal formatting — a point is not the standard decimal separator.
✅ La rezulto estas 3,14.
The result is 3.14.
Reading fractional digits as one cardinal
❌ 46,987 estas kvardek ses komo naŭcent okdek sep.
Incorrect ordinary decimal reading — digits after the comma are read separately.
✅ 46,987 estas kvardek ses komo naŭ ok sep.
46.987 is read forty-six point nine eight seven.
Leaving procento singular after a larger number
❌ La rabato estas tridek procento.
Incorrect — procento is an ordinary count noun.
✅ La rabato estas tridek procentoj.
The discount is thirty percent.
Adding accusative after je
❌ La prezo kreskis je kvin procentojn.
Incorrect — je already marks the phrase's role.
✅ La prezo kreskis je kvin procentoj.
The price rose by five percent.
Using occasions for multiplication
❌ Tri fojojn kvar egalas al dek du.
Incorrect mathematical reading — fojojn counts occasions.
✅ Trioble kvar egalas al dek du.
Three times four equals twelve.
Key Takeaways
Write decimals with a comma and read each fractional digit separately. Treat procento/elcento as a count noun, use de for the whole and je for the amount of change, and distinguish percentages from percentage points. In arithmetic, use plus, minus, multiplikite per, dividite per, and estas/faras/egalas al; use spaces to group large integers and keep mathematical symbols distinct from ordinary Esperanto word formation.
Related Topics
- Cardinal NumbersA1 — Use Esperanto cardinal numbers to count, quantify noun phrases, identify items, and read basic dates, times, measurements, and decimal notation.
- FractionsA2 — Build exact fractions with the official suffix -on-, then use their noun, adjective, and adverb forms with quantities and units.
- Multipliers and RepetitionsA2 — Distinguish multiplication with -obl- from repeated occasions with fojo, and form each pattern productively.
- Distance, Weight, and VolumeB1 — Measure dimensions, separation, weight, and capacity with unit nouns, accusative extent, je and de phrases, and da after quantities.
- Money and PricesB1 — State prices, values, payments, ranges, discounts, and per-unit rates with correct currency nouns, case, and verb frames.
- Technical and Scientific WritingC2 — Write precise Esperanto definitions, methods, results, and technical terminology for an international specialist audience.