Ich esse keine Orangen.
I translated this sentence as "I eat no oranges", which was accepted as correct. I saw that "I do not eat oranges" is also correct. I though nicht negates a verb, while kein (or keine) negates a noun. While the sentences mean the same thing (or very close), why did this sentence use keine rather than nicht?
Keine is for numbers of items... If you can have a number of them (5 oranges) then use keine. Nicht is for "Not" like "Ich kenne ihm nicht"... you don't really number the amount of infamiliarity you have with him.
It depends on how literal you want the translation to be. "I do not eat oranges" has the same meaning (more or less) as "I eat no oranges". Duolingo allows both translations for cases like this, usually, although I have been frustrated from time to time, when I use a more natural or colloquial translation for something, and Duolingo marks it wrong.
It's odd that Duolingo would use "Orange" instead of the more common "Apfelsine".