The article that started this discussion is a case in point. "Europe added almost 23,000,000 km^2" or "Europe added almost 9,000,000 mi^2" are both approximate statements. An automatic conversion would give an unwarranted impression of precision in this case.
Inferring the precision from the number of zerso does not seem like an ideal practice (even if it is used in science). How about writing the numbers as triples
(number,precision,units)
reflecting the fact that these are really intervals or probabilistic distributions centered around "number".
Never send a computer program to do a human's job.
Unless computer can actually do the job, in which case it will probably do it better.
Viktor