Yes, the days of the week do need to be capitalized.
Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday.
Yes
3 days
You have to work every day. You usually have shows six days a week, but you need to practice ad limber
There are 48 week in 336 days
Yes, days of the week are capitalized.
As there are, naturally, 7 days in a week, you need to multiply the number of weeks by 7.
Both "what days of the week" and "which days of the week" are correct; however, "which days of the week" is typically used when the choices are limited, while "what days of the week" is more open-ended.
You need to take any prescribed medication exactly as the doctor prescribed it. If his instructions aren't clear, then you need to ask the pharmacist or doctor to explain them.
Seven days in a week is more generally used than seven days in the week, except if in reference to a specific week such as 'the seven days in the week' when referring to a specific week, such as the week before Christmas.
There are 7 days in a week and there is 4 weeks in a month
13 days = 1 week and 6 days
5 days is one work week, but there are 7 days in a week.