Once you go past a few hundred, French numbers acquire three quirks that English doesn't have: an agreement rule for cent (it takes an -s in some positions and not others), a rule for mille that is the simplest in the language (it never agrees, ever), and a distinction between million / milliard as nouns versus cent / mille as numerals — a distinction that determines whether you need a de before the noun. On top of that, French and English use different scales for the word billion in some contexts, which is one of the most under-flagged false friends in the language. This page covers all of it, with the spelling reform rules and the spoken patterns that native speakers actually use.
Cent — the agreement rule
The word cent agrees in two specific situations and stays invariable everywhere else.
Rule: cent takes a plural -s only when:
- it is multiplied by another number (deux, trois, quatre…), and
- it is not followed by another number.
Il a payé deux cents euros pour la nuit d'hôtel.
He paid two hundred euros for the hotel night. (200 — round, multiplied: cents takes -s)
Il a payé deux cent cinquante euros.
He paid two hundred fifty euros. (250 — multiplied but followed by another number: cent loses the -s)
J'ai dépensé quatre cents euros à Noël.
I spent four hundred euros at Christmas. (400 — multiplied, round)
J'ai dépensé quatre cent quatre-vingts euros.
I spent four hundred eighty euros. (480 — multiplied but trailing number)
For a plain cent (= 100) without a multiplier, no -s ever:
Cent personnes ont assisté à la conférence.
One hundred people attended the conference. (no multiplier — no -s)
Le ticket coûte cent vingt euros.
The ticket costs one hundred twenty euros.
Vingt — the same rule as cent
The number quatre-vingts (= 80) follows exactly the same logic as cent, because historically quatre-vingts is a multiplication (four twenties).
Le musée a quatre-vingts œuvres dans cette salle.
The museum has eighty works in this room. (80 — round, with -s on vingts)
Le musée a quatre-vingt-deux œuvres au total.
The museum has eighty-two works in total. (82 — trailing number, no -s)
The same applies to compound numbers built on quatre-vingts:
Il y avait quatre-vingt-dix invités au mariage.
There were ninety guests at the wedding. (90 — trailing dix, so no -s on vingt)
This cent/vingt symmetry is one of the few internally consistent rules in French numeral morphology.
Mille — the invariable workhorse
Mille never agrees. It has no plural form. Deux mille euros, cinq mille livres, cent mille personnes — always mille, always without -s.
Cette voiture coûte vingt mille euros.
This car costs twenty thousand euros.
La ville compte trois cent mille habitants.
The city has three hundred thousand inhabitants.
Il y a deux mille ans, Jules César a envahi la Gaule.
Two thousand years ago, Julius Caesar invaded Gaul.
The historical reason: mille descends from Latin mille, which had a special invariable behaviour even in Latin, where it functioned as both a numeral and a collective noun (and Romance languages inherit the no-agreement rule).
Note: in dates from the first millennium AD, the literary spelling mil (without the second l) is sometimes used: l'an mil. This is archaic and you will only see it in historical writing.
L'an mil — le passage à l'an 1000 inquiétait les Européens.
The year 1000 — the turn of the millennium worried Europeans. (mil — archaic literary spelling for mille in this fixed phrase)
Million and milliard — nouns, not numerals
Here is the structural break. Cent, mille, and the smaller numerals (deux, vingt, quarante…) are adjectives / numerals — they attach directly to a noun. But million and milliard are nouns, and like any noun they need a de before another noun.
Cette région compte trois millions d'habitants.
This region has three million inhabitants. (millions — noun, takes -s in plural, followed by de)
Le projet coûtera un milliard d'euros.
The project will cost one billion euros. (milliard — noun, takes de)
La planète a perdu deux milliards d'arbres en dix ans.
The planet lost two billion trees in ten years.
Compare with mille (no de):
La ville compte trois cent mille habitants.
The city has three hundred thousand inhabitants. (mille — numeral, direct attachment)
Le projet coûtera mille euros.
The project will cost a thousand euros.
When million is followed by a smaller number
If the millions are joined to another number (millions of thousands and so on), de disappears — the smaller number takes over as the immediate attachment.
Trois millions cinq cent mille habitants.
Three million five hundred thousand inhabitants. (no 'de' — the smaller number absorbs the noun-attachment role)
Un million de personnes ont manifesté.
One million people demonstrated. (with de — million is the last quantifier)
The rule of thumb: de appears when million / milliard is the last quantifier before the noun. When more numbers follow, the attachment runs through them.
Million, milliard, billion — the scale problem
This is the genuinely confusing piece, and it requires care.
In modern French, the standard scale is the long scale:
| French | Numerical value | English equivalent |
|---|---|---|
| un million | 106 (1 000 000) | one million |
| un milliard | 109 (1 000 000 000) | one billion (US/UK modern) |
| un billion | 1012 (1 000 000 000 000) | one trillion (US/UK modern) |
| un billiard | 1015 | one quadrillion |
| un trillion | 1018 | one quintillion |
The false friend is billion. In French it means 1012 (a million millions), which is what English calls a trillion. In modern English (both US and UK), billion means 109 — which in French is milliard.
So the translation chain runs:
- English billion (109) → French milliard
- French billion (1012) → English trillion
Le PIB mondial dépasse cent mille milliards de dollars.
World GDP exceeds 100 trillion dollars. (100 thousand milliards = 10^14 = 100 trillion)
La dette publique française s'élève à environ trois mille milliards d'euros.
French public debt amounts to about three trillion euros. (3 000 milliards = 3 × 10^12 = 3 trillion)
In modern French press and finance, milliard does almost all the work that English does with billion. The word billion does exist and is technically correct (1012), but it is rarely used in everyday writing — even financial journalists prefer mille milliards over un billion because it is less ambiguous.
Building a large number out loud
Reading a number like 1 234 567 out loud requires assembling the pieces left to right. The structure mirrors the digit grouping: millions, then thousands, then the final three.
1 234 567 → un million deux cent trente-quatre mille cinq cent soixante-sept
La population de Paris intra-muros est d'environ deux millions cent quarante mille habitants.
The population of Paris proper is about 2,140,000.
Le prix d'achat de la maison était de quatre cent soixante-quinze mille euros.
The purchase price of the house was four hundred seventy-five thousand euros.
L'humanité dépasse huit milliards de personnes depuis 2022.
Humanity has exceeded eight billion people since 2022.
Note that mille in the middle of a number has no -s even though it follows a plural — that is the universal invariability rule.
No 'and' in compound numbers
English inserts and before the final two digits of a hundred-or-thousand expression: two hundred and one, three thousand and twenty. French does not. The word et appears only in three specific spots:
- vingt et un (21), trente et un (31), quarante et un (41), cinquante et un (51), soixante et un (61), soixante et onze (71 — under the 1990 reform written soixante-et-onze with hyphens)
Everywhere else, the numbers are written with hyphens (or spaces in some styles) and no et:
Il y a deux cent un invités au mariage.
There are two hundred and one guests at the wedding. (no 'et' — French is just deux cent un)
Le livre a trois cent quarante-deux pages.
The book has three hundred and forty-two pages.
J'ai mille trois euros sur mon compte.
I have one thousand and three euros in my account.
Quatre-vingt-un, quatre-vingt-deux, quatre-vingt-trois...
Eighty-one, eighty-two, eighty-three... (note: quatre-vingt-un — no 'et', unlike vingt et un)
The asymmetry between vingt et un (with et) and quatre-vingt-un (without et) is one of the rough edges of French numbering. The reason: in the historic Latin pattern, the conjunction et connected a base to its unit (vingt-et-un = a base of 20 plus 1). When the base itself is multiplied (quatre-vingt = four-twenty), the unit just gets glued on.
The 1990 spelling reform
The 1990 French spelling reform (les rectifications orthographiques) recommended hyphenating every part of a compound number, including the et-clauses:
- vingt-et-un (hyphens)
- soixante-et-onze
- deux-cent-cinquante
- mille-neuf-cent-quatre-vingt-dix-huit (1998)
Both spellings (with hyphens everywhere or hyphens only between juxtaposed numerals) are accepted. Schools after about 2008 teach the reformed system, but the older form remains common in adult writing. Either is fine; consistency within a document matters more than which one you pick.
Common Mistakes
❌ Deux milles euros
Incorrect — mille never takes a plural -s, regardless of the multiplier.
✅ Deux mille euros
Two thousand euros
❌ Trois millions habitants
Incorrect — million is a noun and requires de before another noun.
✅ Trois millions d'habitants
Three million inhabitants
❌ Deux cents cinquante euros
Incorrect — cent loses its -s when followed by another number. The trailing cinquante means no -s.
✅ Deux cent cinquante euros
Two hundred fifty euros
❌ Le budget américain dépasse mille milliards de dollars — un billion.
Ambiguous and likely wrong — un billion in French is 10^12 (English: trillion). One thousand milliards equals one French billion, which in English is one trillion. The English-translation chain should not go through 'billion' here.
✅ Le budget américain dépasse mille milliards de dollars (un billion en français = un trillion en anglais).
The American budget exceeds a trillion dollars (un billion in French = one trillion in English).
❌ Deux cent et un euros
Incorrect — only -et un endings on 21, 31, 41, 51, 61, (71) take 'et'. Numbers ending in 'cent un' or 'mille un' do not.
✅ Deux cent un euros
Two hundred and one euros
❌ Quatre-vingts-deux pages
Incorrect — quatre-vingts loses its -s when followed by another number, same rule as cent.
✅ Quatre-vingt-deux pages
Eighty-two pages
❌ Cents euros
Incorrect — cent alone (= 100) is not multiplied, so no -s.
✅ Cent euros
One hundred euros
Key takeaways
Three rules govern the agreement of large-number words:
- Cent and vingt (in quatre-vingts) take an -s only when multiplied and not followed by another number. Deux cents, deux cent un. Quatre-vingts, quatre-vingt-un.
- Mille never agrees. Ever. Not after a multiplier, not in a plural sum — never.
- Million and milliard are nouns, not numerals. They pluralise normally, and they take de before a noun that follows them: trois millions de personnes.
Beyond agreement, French differs from English in two important ways: it does not insert et between hundreds-or-thousands and their trailing digits (deux cent un, never deux cent et un), and its billion is the long-scale 1012, which is what English calls a trillion. Translators who treat milliard and billion as cognates are responsible for some of the largest published numerical errors in the press. When in doubt, count the zeros.
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Start learning French→Related Topics
- Les Nombres CardinauxA1 — French cardinal numbers from zero to a billion: the regular 1-69, the vigesimal 70-99, the agreement rules on cent and vingt, the noun-like behavior of million and milliard, and the hyphenation rules under both traditional and reformed spelling.
- La Virgule DécimaleA2 — Why French writes 3,14 where English writes 3.14 — the decimal comma, the thousands separator (a space, not a comma), how to read decimals out loud, and the small typographic differences that quietly cause large misunderstandings on invoices, recipes, and spreadsheets.
- Les Prix et l'ArgentA1 — How to read, say, and ask about prices in French — euros and centimes, the comma decimal, the way native speakers actually pronounce €12,50 at the till, and the polite formulas that keep a transaction smooth.
- Pourcentages et FractionsB1 — How French expresses percentages and fractions — pour cent with its mandatory space, the fraction nouns (demi, tiers, quart), agreement with verbs after percentage subjects, the difference between un demi and la moitié, and the gender quirks of demi(e) pre- and post-nominal.
- Les Nombres CardinauxA1 — Cardinal numbers in French — un, deux, trois — function as determiners when they precede a noun. The system is mostly transparent until you reach the famous 70/80/90 zone, where French does arithmetic out loud: soixante-dix (60+10), quatre-vingts (4×20), quatre-vingt-dix (80+10).