"The blue flag has one color."
Translation:La blua flago havas unu koloron.
Do numbers not change with parts of speech? This "one" is modifying color, right? It's an adjective. Wouldn't one expect something like "unuan koloron" ?
Number words in adjective form are ordinal numbers.
unu = one ; unua = first
du = two ; dua = second
tri = three ; tira = third
So even though it should be accusative like ***unun
We don't do that?
It's one of those examples where Esperanto is perfectly regular and logical except when it isn't :P
Only nouns and adjectives take -n endings in accusative. Numbers are not nouns.