It’s really all about numbers and counting right now.
Counting weeks allows both the use of the Native and Sino-Korean numbers although the latter is preferred. Numeral expression for weeks can be as follows:
- 주일 (ju-il) which is literally weeks
- 주간 (ju-kan) means similar to in weeks time or
So to say one week, we can either use 일 주일 (il ju-il) or 한 주일 (han ju-il). Replace 한 with 세 or 삼 then you have 3 weeks in Native and Sino-Korean respectively. Remember the rule with 하나, 둘, 셋 and 넷 when used before counter/noun it counts (the last sound is dropped). Another tip is that when counting weeks the Sino-Korean way, removing 일 (il) would leave 주 (ju) and it will still mean week such that 일 주일 would still mean one week even if its 일 주.
For the expression like:
- Q: How long will it take to finish the project?
- A: In four weeks time.
The answer (A) can be expressed as 네 주간 있어요 (Ne jukan issoyo). This expression is more suitable for stating limit or scope using week as period of measure as in completion of something.