I had a discussion with my (natively French-speaking) in-laws about this some time ago! Essentially, native speakers rely heavily on short pauses in the pronunc

I had a discussion with my (natively French-speaking) in-laws about this some time ago! Essentially, native speakers rely heavily on short pauses in the pronunciation of numbers, causing 3420 to be pronounced "trente quatre vingt", whereas 3080 would be "trente quatrevingt". Relatively hard to pick up on as a foreigner, but second nature to native speakers.