I ask again today a question that will probably be completely trivial for those who know the language.
What is the difference between 一〇〇四六 and 一万四十六 ? Or (I think the difference is the same, but I don't know which it is) between 一九〇九〇 and 一万九千九十 ?
一万四十六 is a single number: "ten thousand fourty six".
一〇〇四六 is a sequence of digits: "one, zero, zero, four, six". This would be kanji spelling of things like telephone numbers, which are in modern times rather always spelt using Arabic numerals.
Analogically for 一万九千九十 and 一九〇九〇.