using hyphens with cent

Question

In the lesson “Expressing numbers 70 to 999 in French” one example is given as:
“trois-cent-quarante    three hundred and forty”
However, in the lesson “Expressing large numbers -thousands/millions/billions - in French” the description begins with: 
“Up to neuf cent quatre-vingt-dix-neuf [choses] (999 [things])”        
Which example is correct? Should there be hyphens between all parts of the number, or just some of them?
Thank you.

Accepted Answer

Bonjour Ruth,
You are correct that this example needs to include the hyphens as per the Spelling Reform and the lesson on Expressing numbers 70 to 999 in French. 
However, when using "millier(s) /million(s) / milliard(s) de" you do not add the hyphen before:

Deux-cent-trente-cinq millions d'euros = Two hundred and thirty-five million euros
Deux-cent-trente-cinq-millions = Two hundred and thirty-five million

Trois-cent-huit milliers de Français = Three hundred and eight thousand French people
Trois-cent-huit-mille = Three hundred and eight thousand

A note has now been added in the lesson to explain this.
I hope this is helpful.
Bonne journée !

Answer

Following the Academy's 1990 recommendations, hyphens are used to link all the words making up a number, except where et is used.Here's a useful resource: https://about-france.com/french/numbers.htm