Korean uses two common number systems. Learners often memorize both lists and still hesitate in conversation because the important question is not “Which word means three?” but “What am I counting?” Learn each system together with its typical situations and counters.
The two basic sets
Native Korean begins 하나, 둘, 셋, 넷, 다섯 (one through five). Sino-Korean begins 일, 이, 삼, 사, 오. Sino-Korean words came historically through Chinese characters and appear in many dates, measurements, prices, addresses, and formal numbers.
Use Native Korean for many counted items
Native Korean is commonly used with counters for people, objects, animals, age in ordinary conversation, and hours on the clock:
- 사과 세 개 — three apples
- 학생 두 명 — two students
- 다섯 시 — five o’clock
- 스무 살 — twenty years old
Several number forms shorten before a counter: 하나 becomes 한, 둘 becomes 두, 셋 becomes 세, 넷 becomes 네, and 스물 becomes 스무.
Use Sino-Korean for dates, money, and minutes
Sino-Korean is normally used for calendar years, months, dates, phone numbers, addresses, prices, minutes, seconds, and numbers in mathematics:
- 삼월 십오일 — March 15
- 오천 원 — 5,000 won
- 십 분 — ten minutes
- 이 층 — second floor
A single time expression uses both
Hours normally use Native Korean, while minutes use Sino-Korean. 세 시 십오 분 is 3:15: 세 is Native Korean, and 십오 is Sino-Korean. This mixed expression is a useful reminder that situation matters more than keeping one system throughout a sentence.
Large numbers are grouped by ten thousand
Sino-Korean large numbers use 만 for ten thousand. Therefore 50,000 is 오만, not a direct word-for-word copy of “fifty thousand.” Prices and population figures become easier after practicing units such as 십 (10), 백 (100), 천 (1,000), 만 (10,000), and 억 (100,000,000).
Age can appear in either system
Native Korean is common in everyday statements of age with 살. Sino-Korean appears with 세 in formal forms, notices, and official contexts. You may therefore encounter 스무 살 and 이십 세 for age twenty in different situations.
A situation-based practice plan
- Say the current hour and minute.
- Read three prices from a Korean shop page.
- Count five objects with 개.
- Say today’s month and date.
- Read a floor number and a phone number.
Practice the noun and counter with the number. A card showing only “three = 셋/삼” hides the decision you must make. A card showing “three people = 세 명” teaches a usable phrase.