Write 6.816 correct to one decimal place
6.8 because you only need one decimal place, you can leave the other two given decimal places out.
We don't know what's
correct, because we don't know anything about
where the number came
from. If you want the number ROUNDED to
one place, that's 6.8 . If you
want it TRUNCATED (shortened, trimmed)
to one place, that's also 6.8 . But we have no idea whether either digit is correct.