"It takes ten days."
とおか and とうか would both be pronounced the same. They're both pronouced とーか, as far as I understand. I'm not sure I've understood your point about spoken language.
- 八 = や
- 十 = とお
八日 is spelt ようか and not よおか because it comes from the modern kana spelling change of やう → よう. (~a + u = ~ō)
十日 is spelt とおか and not とうか because it instead comes from the modern kana spelling change of とを → とお. (~o + wo = ~ō)
I knew an Indian gal named Juhi. But that's not the right pronunciation for 十日 (とうか).
Shouldn't this sentence say 10日間かかります （とうかかんかかります）? which delineates a period of time. It's like a Japanese counter, and seems that a native Japanese speaker would be more likely to say 十日間
とおかかかります was not accepted. I think that's the first time i've seen the kana not being accepted. how odd. Luckily it doesn't erroneously accept じゅうひ, so i guess it's about telling us it's time we HAVE to start using kanji, which is fair.
I don't think even a single one of these "it [takes|took] __ days" sentences accept kana for the number. I've been reporting all of them since before this course even entered beta back in May!
Numbers are pretty much the only risky thing to type in kana in this course. ^^;
I would honestly say anything away from the つ counters (匹、人、etc) in kana is risky 笑笑笑
I don't have a clear answer, i do know a lot of natives tend to drop "easily understood" particles like, 「あの子、早いです。」 or sometimes even 「その雲、怖いだね」. This us almost as colloquial as using じゃけん though, so only omit particles when it feels "safe", and never in formal settings without practice