When the numbers six, dix, etc. quantify a noun, such as in six minutes, dix bananes, the final s sound disappears.
What about when these numbers indicate dates of a month, such as in six janvier, dix mars, etc.?
There are actually three possible situations, depending mainly on the word following six or dix :
To take in consideration : according to the region of France you live in, liaisons and pronounciation of a final letter are subject to change ; in the south, people are more up to pronounce the final x of six & dix as an s, less in the northern half ; there are even some regions (more in the north-eastern country) where the final t in vingt is being pronounced(but not the g), which always surprises me.
If you are asking about the pronunciation of the "s" sound at the end six, dix, then yes, it is not pronounced in six janvier. For dix mars, I am not so sure. I could say it both ways, although without sounds better.