trois milliards is 3 000 000 000. Call them billions in English.
trois cent neuf milliards
"Three billion (3,000,000,000)" is a literal English equivalent of the French phrase trois milliards. The pronunciation of the masculine plural numerical phrase -- which most famously references the movie Trois milliards sans ascenseur ("Three billion without [an] elevator") directed by French actor / producer Roger Pigaut (April 8, 1919 - December 24, 1989) in 1972 -- will be "twa mee-lyar" in French.
trois milliards six cent soixante dix huit millions trois cent soixante quatre mille cinq cent trente neuf. I doubt that it is useful to know by heart.
The cast of Trois milliards sans ascenseur - 1972 includes: Nike Arrighi as Minouche Michel Bouquet as Albert Marcel Bozzuffi as Gus Dany Carrel as Lulu Bernard Fresson as Julien Marcel Gassouk Victor Lanoux as Gino Claude Lochy as Duval Serge Reggiani as Pierrot Pierre Rousseau Jean Solar Yvan Tanguy Francis Terzieff
175 : cent soixante quinze 233 175 : deux cent trente trois mille cent soixante quinze 362 233 175 : trois cent soixante deux millions, deux cent trente trois mille cent soixante quinze 2 362 233 175 : deux milliards, trois cent soixante deux millions, deux cent trente trois mille cent soixante quinze
trente-trois
it's Un, deux, trois. So the answer to your question is trois.
trois.
trois cent quatre
Trois
soixante trois
vingt-trois