Quote Originally Posted by Platinum
un (yeah, all letters are pronounced)
du (not like doo, but more like the first two letters of "done")
twa
katr (I've heard it with the "r" so lightly pronounced that it's barely there)
sank (all the letters are pronounced)
six (I don't know about that)
set
het
nef
dix (I don't know how to say that).

Anyway, this is not a French forum, so I'll shut up now.
In 'un', all the letters are not pronounce, more like "uh" but nasalized. If you raise your tongue to the back of the mouth so air can't pass through, you can make the proper sound.
'Deux' is not pronounced as the first two letters "done". I'm not sure how to write it linguistically yet. If you say "uh" again and then round the mouth, you'll make the sound. (Technique I learned in linguistics to pronounce sounds )
In 'quatre' the "r" is pronounced, though not in the way it is in Russian. It's a rolling of the "r" in the back of the throat.
In 'six' the "x" is pronounced the same as the "s". sees (not the English "sees" though) Using the IPA (International Phonetic Alphabet) it would be "sis". "i" is pronouced "ee". Same with 'dix'.

Huit is not pronounced "het". It's pronounced more like "wheat".
Neuf is pronounced with the 'eu' sound in 'deux'.

Why are you discussing a language you know nothing about?

Here is a link with all the number pronunciations. http://french.about.com/library/begin/bl_numbers.htm