"사흘은 사일이 아니에요."

Translation: Three days are not four days.

[Jessica988165]

More correct would be "3 days is not 4 days."

[Jessica396502]

I did the same thing again. -.-

[marta_barnes]

In both cases the word is prefixed with "사" which I thought meant 4. How do we tell which one means 3?

[josueetcom]

사 and 일 are of Sino-Korean origin whereas the equivalent Native Korean words are 넷 and 날. With periods of time when there's words of both Sino-Korean and Native Korean origins, you use Sino-Korean numbers with the Sino-Korean words and Native Korean numbers with Native Korean words.

As for 사흘 you sort of need to just memorize it. But, it's of Native Korean origin so it's based on the Native Korean 셋 rather than the Sino-Korean 사.

[Andro0]

'사흘' means '3 days'.. '나흘' means '4 days'. You just need to memorize

[alexis_lew1]

so if you use 흘 it's the native Korean numbers, and 일 uses the Sino-Korean numbers? how come it's not 세흘 and 네흘? or is it completely unrelated to native Korean numbers?

[emsuzz]

this set of numbers is one you just have to memorize and that's why a lot of people don't use it.

[AnnaKarolina89]

Well, that's confusing

[BobaBunny5]

Why do they use a mix of Korea and Chinese origin?" Why not "삼일은 사일이 아니에요?" or "사흔을 나흘이 아니에요."

[Pamela909830]

The point is teaching the difference between the two words with the same syllable 사. One means 3 and the other means 4. So we have to look at the context to know the difference. When we see the Chinese (Sino-Korean) word 일, we know to use the Chinese (Sino-Korean) number 4, but when we see the Korean expression 사흘, we have memorized that it means 3 days. See the excellent explanation by josueetcom up higher in the comments, and the top comment by Andro0, which is a list we all need to memorize. :)

[Jweg61]

Because Koreans use a mix, so to teach us everything properly we must also learn the mix

[Andro0]

One day = 하루

Two days = 이틀

Three days = 사흘

Four days = 나흘

Five days = 닷새

Six days = 엿새

Seven days = 이레

Eight days = 여드레

Nine days = 아흐레

Ten days = 열흘

[KanKanMikan]

oh great, here we go again, take month for me to remember all the native number, and there's completely different word for counting days?

[suhandiwiratama]

Fifteen days = 보름,

One month = 한 달

[Pamela909830]

Interesting! I never saw the word "보름" before. Thanks.

[Sebihoo]

Kill me now..

[baelasi]

very conpusing

[mtztdl]

When do you use both forms? Like what form would be suitable for a certain a situation?

[Ash-Fred]

There should be a space between 사 and 일. I just disabled this exercise and made a new one with the error corrected. We are sorry for the confusion.

[ThomasWelc4]

I'm apparently missing something, because, to me, use of the word "사" in both places establishes that the sentence says "사흘은 사일이 아니에요., meaning "Four days are not four days." Where did the "삼" come from?

[Andro0]

'사흘' means '3 days' you just have to memorize that

[SteveKlyns]

사흘 must be memorized as Andro0 indicates and means three days. 사일 combines the sino-korean number for 4 or "사" with the korean word for day "일"

[Pamela909830]

일 is the sino-korean word for day. 날 is the Korean word.

[Fauziaaang]

Remember this

[jaisaige]

This made me mad..

[Pamela909830]

Why? Go up to the very top comment by Andro0. He wrote a list that we all need to memorize. (My teacher made me memorize it a few years ago.) After you memorize those phrases, AND remember the difference between the Sino-Korean (from Chinese) 일 = day and native Korean 날 = day, this question is much easier. YES, having to learn 2 different number systems is difficult, but you can do it. :)