Why Korean Has Two Number Systems
Korean uses two completely different number systems, and knowing when to use each one is essential for fluent communication. Native Korean numbers (고유어 수사, goyueo susa) come from the original Korean language and have been used on the peninsula for thousands of years. Sino-Korean numbers (한자어 수사, hanjaeo susa) were borrowed from Chinese and entered Korean through centuries of cultural exchange and the use of Classical Chinese as a literary language. Each system is used in specific contexts, and mixing them up is a common mistake for learners that immediately marks speech as non-native. Even telling time requires both systems — native Korean for hours and Sino-Korean for minutes. Mastering this dual system is a fundamental milestone in Korean language learning, and daily practice with real situations like shopping and scheduling will help you internalize which system to use. The reason Korean maintains two systems rather than simplifying to one is deeply tied to history and linguistic habit. Native Korean numbers feel more colloquial and personal, which is why they are used for concrete, everyday counting — how many items, how old someone is, what hour it is. Sino-Korean numbers feel more precise and academic, which is why they dominate mathematics, dates, currency, and anything involving larger quantities. Think of it as two modes: native Korean numbers for the tangible world around you, and Sino-Korean numbers for abstract or systematic counting. Most learners find that native Korean numbers from 1-10 come quickly, but the teens (열하나, 열둘) and larger numbers (스물, 서른, 마흔, 쉰) require more deliberate memorization.
Numbers 1-10 in Both Systems
| Number | Native Korean | Sino-Korean |
|---|---|---|
| 1 | 하나 (hana) | 일 (il) |
| 2 | 둘 (dul) | 이 (i) |
| 3 | 셋 (set) | 삼 (sam) |
| 4 | 넷 (net) | 사 (sa) |
| 5 | 다섯 (daseot) | 오 (o) |
| 6 | 여섯 (yeoseot) | 육 (yuk) |
| 7 | 일곱 (ilgop) | 칠 (chil) |
| 8 | 여덟 (yeodeol) | 팔 (pal) |
| 9 | 아홉 (ahop) | 구 (gu) |
| 10 | 열 (yeol) | 십 (sip) |
When to Use Each System
| Use Native Korean For | Use Sino-Korean For |
|---|---|
| Counting objects (1-99) | Numbers above 100 |
| Age (살) | Dates (년, 월, 일) |
| Hours (시) | Minutes (분) and seconds (초) |
| Counting people (명/분) | Money (원) |
| Small quantities | Phone numbers and addresses |
Watch Out: Numbers That Change Form
When native Korean numbers 1-4 and 20 are placed before a counter, they change form: 하나→한 (han), 둘→두 (du), 셋→세 (se), 넷→네 (ne), 스물→스무 (sumu). For example, 하나 becomes 한 in 한 개 (han gae — one item). This is one of the trickiest parts of Korean numbers and the area where learners make the most mistakes. The reason for these changes is phonological convenience — the shortened forms flow more naturally before counter words. Note that these changes only happen before counters, not when counting alone. If someone asks 몇 개? (myeot gae — how many?) you answer 세 개 (se gae — three items), not 셋 개. But if someone asks you to count, you say 하나, 둘, 셋 (hana, dul, set) with the full forms. Numbers 5 through 19 do not change form before counters, which provides some relief. Also note that 20 changes to 스무 only before 살 (sal, years old): 스무 살 (sumu sal, 20 years old), but 스물 한 살 (seumul han sal, 21 years old) uses 스물 as the base with 한 following.
Using Both Systems Together
지금 세 시 삼십 분이에요. 커피 두 잔에 만 이천 원이에요.
Jigeum se si samsip bun-ieyo. Keopi du jan-e man icheon won-ieyo.
It's 3:30 right now. Two cups of coffee are 12,000 won.
Practical Situations: Which Number System to Use
The most confusing aspect of Korean numbers for learners is remembering which system to apply in which real-life situation. Here is a comprehensive breakdown of the most common scenarios. When shopping, use Sino-Korean for prices: 오천 원 (ocheon won, 5,000 won), 만 삼천 원 (man samcheon won, 13,000 won). But when telling the cashier how many items you want, use native Korean: 두 개 주세요 (du gae juseyo, two items please). When telling time, use native Korean for hours — 세 시 (se si, 3 o'clock) — and Sino-Korean for minutes — 이십 분 (isip bun, 20 minutes). For dates, everything is Sino-Korean: 이천이십육 년 사월 십육 일 (2026-nyeon sawol simnyuk-il, April 16, 2026). For age, use native Korean with the counter 살: 스물다섯 살 (seumuldaseot sal, 25 years old). Phone numbers use Sino-Korean digits read one by one: 공일공 (gong-il-gong, 010). When counting people at a restaurant, native Korean is used with the counter 명 (myeong): 세 명이요 (se myeong-iyo, three people). Floors in a building use Sino-Korean with 층 (cheung): 삼 층 (sam cheung, third floor). Learning these context rules through practice and repetition is far more effective than trying to memorize them as abstract rules.