Nous sommes quatre-vingt-dix.

Nous sommes is the 1st person plural form of the verb être (to be) in the present tense.

• nous = we
• sommes = are

So grammatically, nous sommes = we are.

This is the same verb you see in:

• je suis = I am
• tu es = you are
• il/elle est = he/she is
• nous sommes = we are
• vous êtes = you are
• ils/elles sont = they are

Because the sentence is using the verb être (to be), not avoir (to have).

French often uses être in sentences that identify or describe a group:

• Nous sommes trois. = We are three.
• Nous sommes vingt. = We are twenty.
• Nous sommes quatre-vingt-dix. = We are ninety.

In English, this can sometimes sound slightly unusual unless the context is clear, but in French it is a normal way to say how many people are in a group.

However, for age, French uses avoir, not être:

• Nous avons quatre-vingt-dix ans. = We are ninety years old.

So nous sommes quatre-vingt-dix is about number of people, not age.

A careful approximate pronunciation is:

katr-van-dees

More precisely in IPA, it is usually:

/katʁə vɛ̃ dis/

A few helpful points:

• quatre sounds roughly like katr
• vingt here sounds like van with a nasal vowel; the g and t are not normally pronounced
• dix here is pronounced dees

So the whole number flows together as:

quatre-vingt-dix → katr-van-dees

This is one of the famous features of French numbers. Quatre-vingt-dix literally means four-twenty-ten, or more naturally, four twenties plus ten.

French builds some numbers in a base-20 pattern:

• quatre-vingts = 80
• quatre-vingt-un = 81
• quatre-vingt-dix = 90

So:

• quatre = four
• vingt = twenty
• quatre-vingts = four twenties = 80
• then add dix = 10
• 80 + 10 = 90

This may feel strange to an English speaker, but it is standard French.

Note: in Belgium, Switzerland, and some other French-speaking areas, you may also hear nonante for 90. But in standard France French, quatre-vingt-dix is the usual form.

French numbers are commonly written with hyphens between their parts.

So you write:

• vingt-et-un
• trente-deux
• quatre-vingt-dix

This helps show that the whole expression is one number.

You may notice some variation in older texts or style conventions, but for learners, using hyphens in forms like quatre-vingt-dix is the safest and most standard choice.

Great question. This is a very common point of confusion.

French writes:

• quatre-vingts = 80
• quatre-vingt-dix = 90

Why the difference?

Vingt takes an s only when it is multiplied and nothing follows it.

So:

• quatre-vingts = 80 → s appears because the number stops there
• quatre-vingt-un = 81 → no s, because another number follows
• quatre-vingt-dix = 90 → no s, because dix follows

So in your sentence, quatre-vingt-dix has no s because the number is not ending at vingt.

No, not by itself.

Nous sommes quatre-vingt-dix means something like There are ninety of us or We are ninety.

If you want to say We are ninety years old, French does not use être. It uses avoir:

• Nous avons quatre-vingt-dix ans.

This is one of the big differences between French and English:

• English: We are ninety years old
• French: We have ninety years

So if you see nous sommes quatre-vingt-dix, do not interpret it as age.

Yes, it can be natural if the context is clear.

It means that the group contains ninety people. For example, someone might say it when counting participants, students, guests, or team members.

Depending on context, French speakers might also say:

• Nous sommes quatre-vingt-dix personnes. = We are ninety people.
• Il y a quatre-vingt-dix personnes. = There are ninety people.
• On est quatre-vingt-dix. = We’re ninety. / There are ninety of us.

So your sentence is grammatical and understandable, but sometimes French adds personnes for clarity.

Yes, very often in everyday spoken French.

Instead of Nous sommes quatre-vingt-dix, people commonly say:

• On est quatre-vingt-dix.

In modern spoken French, on often means we, even though grammatically it is singular.

So:

• Nous sommes quatre-vingt-dix = more formal or careful
• On est quatre-vingt-dix = very common in conversation

Both can mean the same thing here.

No. As a number, quatre-vingt-dix itself does not change for gender.

You use the same form with masculine and feminine nouns:

• quatre-vingt-dix hommes = ninety men
• quatre-vingt-dix femmes = ninety women

The main spelling issue to remember is the special s rule with quatre-vingts for exactly 80, but in quatre-vingt-dix, the form stays the same.

Not normally. Nous sommes quatre-vingt-dix is understood as we are ninety or there are ninety of us.

If you want to talk about the decade, French would use a different expression, such as:

• Nous sommes dans les années quatre-vingt-dix. = We are in the nineties.

So the sentence you were given is about the number 90, not the decade the 1990s.