I forgot which but there is a clan that made a written language. At least according to the James Cameron Avatar Fandom.
No concept of math besides the bare-bone basics of addition and subtraction, none going above 16 obviously as everything above was just a bunch, they didn't even have a shred of a written language! As primitive as the Na'vi may be on the technological aspect, this lack of anything noteworthy on that aspect was puzzling for Liam.