Numbers, Dates & Measurements — I can use numbers, dates,...

SECTION 1

Historical Context & Motivation

Every language develops its own system for expressing quantities, dates, and measurements, and French is no exception. The French number system carries traces of ancient Celtic and Latin counting traditions that make it fascinatingly different from English. Understanding how French handles numbers, dates, and measurements is essential for practical tasks like shopping in a Parisian market, reading a French train schedule, or discussing distances during a road trip through Provence.

Unlike English, which adopted a fully decimal (base-10) counting system, French retains elements of a vigesimal (base-20) system inherited from the Gauls, the Celtic people who inhabited France before the Roman conquest. This is why the number 80 in French is quatre-vingts (literally "four twenties") rather than a simple modification of a base-ten word. These historical layers give the French number system its unique character and also explain some of the patterns that may seem irregular at first glance.

50 BCE

Gaulish Counting Traditions

The Gauls used a base-20 (vigesimal) counting system. When the Romans conquered Gaul, Latin and Celtic counting traditions began to merge, planting the seeds of the modern French number system.

842 CE

The Serments de Strasbourg

The earliest known document in Old French shows how spoken Latin had evolved into a distinct Romance language. Number words and date expressions had already diverged significantly from classical Latin forms.

1539

Ordonnance de Villers-Cotterêts

King Francis I mandated French as the official language of law and administration. Standardized date formats and numerical expressions became essential for legal documents throughout the kingdom.

1795

Adoption of the Metric System

Revolutionary France became the first country to adopt the metric system. French measurement vocabulary — mètres, litres, kilogrammes — spread globally. France also introduced a decimal comma rather than a decimal point.

1990

French Spelling Reforms

The 1990 orthographic reforms recommended hyphens between all elements of compound numbers, simplifying written expressions like vingt-et-un (previously vingt et un).

With this rich history in mind, the central question for French 2 students becomes: how do you accurately produce and understand numbers, dates, time expressions, prices, distances, and durations in everyday French? Let's build that skill set systematically.

SECTION 2

Core Principles & Definitions

Before diving into specific rules, it helps to understand the foundational principles that govern how French expresses numerical and measurement information. These principles differ from English in several key ways, and recognizing them early will save you from common errors.

Base-20 Remnants in Counting

French numbers from 70 to 99 use a combination of base-20 and base-10 logic. For example, soixante-dix (70) means "sixty-ten" and quatre-vingt-dix (90) means "four-twenty-ten." Mastering this range is the biggest hurdle in French numbers.

Day-Month-Year Date Order

French dates always follow the order day / month / year (le 14 juillet 2025), never month/day/year as in American English. Cardinal numbers are used for all dates except the first of the month, which takes the ordinal premier.

The 24-Hour Clock Is Standard

While conversational French may use a 12-hour format with context clues, official time (schedules, tickets, announcements) uses the 24-hour clock. So 3:00 PM is quinze heures (15h00).

Commas and Periods Swap Roles

In French, a comma separates decimals (3,50 €) while a period or space groups thousands (1.000 or 1 000). This is the opposite of English conventions and a common source of confusion.

Metric System Vocabulary

France uses the metric system exclusively. Distances are in kilomètres, weights in kilogrammes, and temperatures in degrés Celsius. Knowing the vocabulary for units is essential for real-world communication.

✦ KEY TAKEAWAY

Think of French numbers like a combination lock: once you know the pattern for each "dial" (1–16 unique words, 17–69 predictable compounds, 70–99 base-20 blends), you can unlock any number. The date and measurement systems are similarly pattern-based — learn the template, and you can fill in any values.

SECTION 3

Visual Explanation — The French Number Map

This diagram maps the entire French number system into four zones: unique words (0–16), predictable compounds (17–69), base-20 blends (70–99), and hundreds/thousands. Key spelling rules are summarized at the bottom.

The diagram above illustrates how French numbers fall into distinct "zones" of difficulty. The first zone (0–16) simply requires memorization of unique vocabulary. The second zone (17–69) follows a regular pattern of tens-word plus units, much like English. The real challenge appears in the third zone (70–99), where the base-20 logic kicks in: 70 is expressed as "sixty-ten," 80 as "four-twenties," and 90 as "four-twenty-ten." Once you understand this structural pattern, what initially seems chaotic becomes entirely predictable.

SECTION 4

How It Works — Dates, Time & Measurement Patterns

Expressing Dates in French

French dates follow a strict template. The formula is: le + cardinal number + month + year. For example, July 4, 2025 becomes le quatre juillet deux-mille-vingt-cinq. The only exception is the first of any month, which uses the ordinal premier: le premier janvier (January 1st). Days of the week and months are never capitalized in French unless they begin a sentence.

DATE FORMULA

le + [cardinal number] + [month] + [year]

Exception: le premier for the 1st of any month. Written format: le 25 décembre 2025 or 25/12/2025.

Telling Time in French

In conversational French, time is expressed using il est + the hour + heure(s) + the minutes. For half past, French uses et demie; for quarter past, et quart; and for quarter to, moins le quart. In formal/official contexts, the 24-hour clock replaces these expressions entirely: 15h30 is read as quinze heures trente with no "et demie."

TIME FORMULA (CONVERSATIONAL)

Il est + [hour] + heure(s) + [minutes / et quart / et demie / moins le quart]

Special cases: midi (noon) and minuit (midnight) replace the number. Use du matin / de l'après-midi / du soir for AM/PM distinctions when needed.

Prices, Distances & Duration

When discussing prices in French, the currency symbol (€) follows the number, and decimals use a comma: Ça coûte 12,50 € (It costs 12.50 euros). To ask the price, you say Combien ça coûte ? or C'est combien ? For distances, French uses kilometres exclusively: Paris est à 460 kilomètres de Lyon. For duration, key structures include pendant (for/during), depuis (since/for ongoing actions), and en (in, to express how long something takes): Le voyage dure trois heures (The trip lasts three hours).

PRICE EXPRESSION

Ça coûte + [number] + euro(s) / Ça fait + [number] + euro(s)

Decimal comma: 3,75 € is spoken as trois euros soixante-quinze (the word centimes is usually omitted in speech).

SECTION 5

Detailed Breakdown — Dates, Time & Measurement in Context

This reference chart shows French formats for dates, time (conversational and 24-hour), prices with the decimal comma, distances in the metric system, and duration expressions with pendant, depuis, and en.

Common French expressions for dates, time, prices, distances, duration, and weight

Category	French Expression	English Equivalent
Date	le 15 mars 2025	March 15, 2025
Date (1st)	le premier avril	April 1st
Time (casual)	Il est deux heures et demie	It's 2:30
Time (official)	Il est quatorze heures trente	It's 14:30 / 2:30 PM
Price	Ça coûte vingt-cinq euros cinquante	It costs €25.50
Distance	C'est à trois kilomètres d'ici	It's 3 km from here
Duration	Le film dure une heure quarante-cinq	The movie lasts 1 hour 45 minutes
Weight	Je voudrais 500 grammes de fromage	I'd like 500 grams of cheese

⚠️ Watch Out: pendant vs. depuis vs. en

These three prepositions all translate to "for" in English but are used in different contexts. Pendant describes a completed duration ("I studied for two hours"). Depuis describes an ongoing action that started in the past and continues now ("I have been studying French for three years"). En tells how long something takes to complete ("I finished the test in 30 minutes"). Mixing these up is one of the most common errors for English speakers.

SECTION 6

Worked Example — Planning a French Trip

Imagine you're describing a day trip from Paris to Versailles to a French-speaking friend. You need to express dates, times, prices, distances, and duration. Let's build each sentence step by step.

Describing a Day Trip: Paris to Versailles

Step 1 — State the DateYou want to say "We are going on Saturday, March 22, 2025." In French, the day of the week comes first (without a capital), then le + the cardinal number + the month. Since 22 is not the 1st, we use the cardinal number vingt-deux. The month mars is lowercase.

Nous y allons samedi, le vingt-deux mars deux-mille-vingt-cinq.

Step 2 — State the Departure Time"We leave at 9:15 AM." In conversational French, use il est for telling time, but for scheduling, you use à + time. 9:15 uses et quart (quarter past). Since it's morning, add du matin for clarity in conversation, or use 9h15 in writing.

Nous partons à neuf heures et quart du matin.

Step 3 — Express the Distance"Versailles is about 20 kilometres from Paris." Use the structure [place] est à [number] kilomètres de [place]. The word environ means "about" or "approximately."

Versailles est à environ vingt kilomètres de Paris.

Step 4 — Express the Duration"The trip takes about 45 minutes by train." For how long something takes, use en or state it with dure (lasts). The number 45 is quarante-cinq. "By train" is en train.

Le trajet dure environ quarante-cinq minutes en train.

Step 5 — State the Ticket Price"The round-trip ticket costs 14.80 euros." In French, a decimal comma separates euros from centimes: 14,80 €. The number 14 is quatorze, and 80 is quatre-vingt — without the -s. In a price context, the cents figure functions as an adjective modifying an implied noun (centimes), so vingts drops its -s. The -s is only kept when quatre-vingts stands alone as an absolute numeral with nothing following (e.g., page quatre-vingts). "Round-trip" is aller-retour.

Le billet aller-retour coûte quatorze euros quatre-vingt.

✅ Putting It All Together

Here is the complete description: Nous y allons samedi, le vingt-deux mars. Nous partons à neuf heures et quart du matin. Versailles est à environ vingt kilomètres de Paris. Le trajet dure environ quarante-cinq minutes en train. Le billet aller-retour coûte quatorze euros quatre-vingt. Notice how every sentence uses a different type of numerical expression — date, time, distance, duration, and price — all in natural, flowing French.

SECTION 7

Common Pitfalls & How to Avoid Them

English speakers commonly make certain predictable errors when using French numbers, dates, and measurements. Understanding these pitfalls will help you avoid them and build accuracy faster.

Common errors English speakers make with French numbers, dates, and measurements

Common Error	Why It Happens	Correct French
Writing "le 1 mars" for March 1st	English uses ordinals for all dates; French only uses premier for the 1st	le premier mars (but le deux mars for the 2nd)
Capitalizing months/days: "Janvier", "Lundi"	English capitalizes these; French does not	janvier, lundi (lowercase)
Saying "quatre-vingt-un" with -s on vingt	Forgetting that vingts drops -s when followed by another number	quatre-vingt-un (no -s); quatre-vingts (80 alone keeps -s)
Using a decimal point: 3.50 €	English uses a period for decimals; French uses a comma	3,50 € (comma, not period)
Using "et demie" with the 24-hour clock	Mixing conversational and official time formats	Official: quinze heures trente; Casual: trois heures et demie
Using depuis with passé composé	English says "I have studied for 3 years" (present perfect); French uses present tense with depuis	J'étudie le français depuis trois ans (present tense, not passé composé)

✦ KEY TAKEAWAY

Think of the comma/period swap in French numbers like driving on the other side of the road in the UK — everything works the same way, it's just mirrored. Once you internalize the switch (comma = decimal, period or space = thousands), it becomes second nature. The same principle applies to date order: just remember that French dates read like a zoom lens, going from the smallest unit (day) to the largest (year).

SECTION 8

Connection to Advanced French — Beyond the Basics

The number, date, and measurement skills you're building in French 2 form the foundation for more advanced applications in French 3 and beyond. As your language proficiency grows, you'll encounter increasingly complex situations that build on these same patterns.

How French 2 number and measurement skills connect to advanced French

French 2 Skill	Advanced Application (French 3+)
Basic prices (Ça coûte 15 €)	Negotiating, comparing prices, discussing budgets, understanding financial news
Simple dates (le 14 juillet)	Historical narrative (En 1789...), using temporal expressions like à cette époque-là, au cours du siècle
Basic time (Il est trois heures)	Complex scheduling, subjunctive with time clauses (avant que, jusqu'à ce que)
pendant / depuis / en	Nuanced tense selection: imparfait with depuis vs. passé composé with pendant; il y a...que constructions
Metric measurements	Scientific descriptions, recipe instructions with precise quantities, technical writing
Numbers to thousands	Large numbers in statistics, percentages (pour cent), fractions (un tiers, trois quarts), approximations (une dizaine, une centaine)

You'll also discover that Belgian and Swiss French use different words for 70, 80, and 90. In Belgium and Switzerland, septante (70) and nonante (90) follow a purely decimal pattern, and Swiss French adds huitante (80). These regional variations highlight how the base-20 system in France is a historical choice, not a universal feature of the French language. As you advance, awareness of these Francophone variations will deepen your cultural competency and make you a more versatile speaker.

SECTION 9

Practice Problems

PROBLEM 1 — CONCEPTUAL

Why does French use quatre-vingts for 80 instead of a simpler base-10 word like huitante? Explain the historical reason, and identify at least one other number in the 70–99 range that reflects the same base-20 pattern.

PROBLEM 2 — BASIC CALCULATION

Write the following date in French: August 17, 2025. Then write it in the standard French numerical format (DD/MM/YYYY).

PROBLEM 3 — INTERMEDIATE

Your train departs at 16h45 and arrives at 19h10. Express both times in conversational French (12-hour format), and state how long the trip lasts using the correct duration structure.

PROBLEM 4 — APPLIED

You are at a French bakery. You buy 2 croissants at 1,20 € each and a baguette for 1,10 €. Write a short dialogue in French where you ask the baker the total price and the baker responds with the amount. Include at least one sentence about distance (the bakery is 500 meters from your hotel).

PROBLEM 5 — CRITICAL THINKING

A French exchange student writes you an email: "Je suis arrivé le 09/01/2025. J'étudie ici depuis trois mois. Le vol a duré huit heures. Mon billet a coûté 780 €. L'université est à quatre-vingt kilomètres de l'aéroport." Identify all the numerical and measurement expressions, translate the email into English, and find the one grammatical error related to this lesson's content.

SUMMARY

Lesson Summary

French numbers are built on a system that blends base-10 and base-20 (vigesimal) patterns inherited from the Gauls. Numbers 0–16 require memorization, 17–69 follow predictable compound patterns, and 70–99 use the distinctive base-20 logic (soixante-dix, quatre-vingts, quatre-vingt-dix). Key spelling rules include: vingt and cent take -s only when multiplied and nothing follows, and mille is always invariable. French dates follow day/month/year order with cardinal numbers (except le premier for the 1st), and months and days are never capitalized.

For time, conversational French uses expressions like et demie, et quart, and moins le quart, while official contexts use the 24-hour clock with simple number addition. Prices use a decimal comma (3,50 €), distances are always in metric units, and duration expressions depend on context: pendant for completed actions, depuis for ongoing actions, and en for how long something takes. Mastering these patterns will allow you to navigate shopping, travel, scheduling, and everyday conversation in French with confidence and accuracy.