"Let's make it in four days!"

Translation: 나흘안에 만들어요!

[Dave2022]

I'm partly fluent in Korean, and I've never heard of "나흘", I've always heard of "넷일/사일". If the one I heard more often is the more common term, why teach the one less heard of?

[wintertriangles]

나흘 is the grammatically correct way to count 4 days. 사일 is the lazy way, as my Korean friends tell me.

[Wanda_1212]

Could somebody tell me what -안 means?

[Staszek456]

In / inside

[Mariam675031]

To do some job within four days if it usually takes 5?

[AbeVallerian]

Why ”나흘 동안 만들어요" is incorrect?

[the_crait]

Can someone come up witj a hypothetical where this sentence may be used?

[fi88r]

When you are learning Korean through Duolingo.