Article in English: In Korean, you will encounter two completely different sets of words for numbers, one based on Korean words and one related to Chinese (this system is sometimes called Sino-Korean). In most cases, if you are simply counting from 1 to 10 (and are not using money or other special cases), you will want to use the Korean system (this is also true in Taekwondo).  Korean numbers are written using symbols that are called “Hangul” and are not written using the Roman alphabet.  Thus, the Roman alphabet spellings of the words vary from site-to-site and are phonetic.   1 하나 (Hana or Hah - nah) 2 둘 (Dul or Dool) 3 셋 (Set or Seht) 4 넷 (Net or Neht) 5 다섯 (Dausut or Dah suht) 6 여섯 (Yeosut or Yuh suht) 7 일곱 (Ilgup or eel gob) 8 여덟 (Yeodul or yuh duhl) 9 아홉 (Ah-hope or ah hob) 10 열 (Yuhl)   Remember: Koreans use both systems depending on the situation. So, for example, the word 10 might be spoken using two entirely different words depending on what’s being counted.  However, most objects are counted using the Korean system unless the counting involves money. So books, people, trees, and any number of objects also use the Korean numbers. Korean forms are used for the number of items from 1 to 60 and age. The Chinese forms are used for things like dates, phone numbers, money, addresses, and numbers over 60.  1 일 (eel) 2 이 (ee) 3 삼 (sahm) 4 사 (sah) 5 오 (oh) 6 육 (yoogh) 7 칠 (Chil) 8 팔 (Pahl) 9 구 (Goo) 10 십 (Shib) There are some special cases in which the Chinese-related system is used even for smaller numbers, though, including addresses, phone numbers, days, months, years, minutes, units of length, area, weight, volume, and numbers after a decimal point.   Generally, though, use the Chinese system for numbers after 60.   Although you should usually use the Korean system for simple 1-10 counting in Taekwondo, you should use the Chinese system when describing a person’s rank. Thus, a first-degree black belt is an “eel dahn,” using the Chinese system word for 1 (“eel”). There are also two ways to say zero, but both are Chinese...

Summary in Indonesian:
Latihlah diri Anda untuk menghafal dua sistem angka. Selain sistem Korea, ada baiknya juga mempelajari dan menguasai sistem Sino-Korea. Hafalkan juga angka nol dalam bahasa Korea.