When to use to not know in Korean
Korean: 모르다[ mo-reu-da ]

When to use it
모르다 means "to not know" or "to be unaware." Use it when you do not know a fact, a person, an answer, or how to do something. In daily conversation, you will often hear the polite form "몰라요" for "I don't know."
Example sentences
저는 요리할 줄 몰라요.
I don't know how to cook.
저는 그 답을 몰라요.
I don't know the answer.
저 사람을 몰라요.
I don't know that person.
이 가게가 몇 시에 닫는지 몰라요.
I don't know what time this store closes.
우리는 서울역 가는 길을 몰라요.
We don't know the way to Seoul Station.
아이는 아직 숫자를 몰라요.
The child does not know numbers yet.