Pay attention on the deference between よっか 四日 and ようか 八日。
Is it ようか or よおか？
ようか. The second one may have just been you remembering とおか.
Why are you talking about the 8th day here ?
is four days pronounced the same as the fourth day?
The kanji of かかる(掛かる) is not accepted.
Shoudn't it be 4日 かん かかるます
That means "it takes a period of 4 days"
"It takes 4 days"
When 間 is used, usually it refers to an effort or an activity that is continuous and non-stop process
My question: "It takes four days..." before something happens after not continuously happening OR "It takes four days..." duration for happening, i.e. "It takes four days for the parcel to arrive." vs "The operation lasts for four hours." ?
Why is a particle not needed?
I believe because the main subject (the thing or task that takes that time) is not mentioned else it usually follows the main subject, please correct me if i am wrong.