Right when you feel comfortable reading Hangul, Korean hands you one of its best-known traps: there are two competing number systems, and real sentences use both at the same time. The good news is the split follows a clear rule. Once you see the division, "why is it 일 in one place and 하나 in another?" stops being a mystery.
The two systems in two lines#
| System | Looks like | Used for |
|---|---|---|
| Sino-Korean (일 이 삼…) | Comes from Chinese numerals | money, dates, phone numbers, minutes, floors, math |
| Native Korean (하나 둘 셋…) | Genuinely Korean | counting things, hours, age, "how many" |
Sino-Korean is the "number" for fast/abstract math. Native Korean is the "number" for pointing at physical things.
Sino-Korean: 일 이 삼 사 오…#
The backbone is 1–10: 일(1) 이(2) 삼(3) 사(4) 오(5) 육(6) 칠(7) 팔(8) 구(9) 십(10). The pattern above ten is wonderfully compact:
| Number | Sino | Breakdown |
|---|---|---|
| 11 | 십일 | 십(10) + 일(1) |
| 20 | 이십 | 이(2) + 십(10) |
| 99 | 구십구 | 9·10·9 |
| 100 | 백 | — |
| 1,000 | 천 | — |
돈: 5,000원 = 오천 원. Phone: 010-… = 공일공… (zero = 공). Time: 15분 = 십오 분.
Native Korean: 하나 둘 셋 넷…#
하나(1) 둘(2) 셋(3) 넷(4) 다섯(5) 여섯(6) 일곱(7) 여덟(8) 아홉(9) 열(10).
The tens are where English speakers grin and groan — they do not follow "twenty, thirty." You must memorize them:
| Tens | Native |
|---|---|
| 20 | 스물 |
| 30 | 서른 |
| 40 | 마흔 |
| 50 | 쉰 |
| 60 | 예순 |
| 70 | 일흔 |
| 80 | 여든 |
| 90 | 아흔 |
The good news: above 19, native numbers rarely appear in learner life (90). The everyday native numbers are 1–10 plus hours and counts.
The rule that decides everything#
Before you reach for a number, ask: am I counting abstract units (money, time, date) or physical individual things?
| You need | System | Example |
|---|---|---|
| Price | Sino | 3,000원 = 삼천 원 |
| Phone number | Sino | 010 = 공일공 |
| Date (month/day) | Sino | 5월 3일 = 오월 삼일 |
| Minutes | Sino | 10분 = 십 분 |
| Age | Native | 25살 = 스물다섯 살 |
| Hours ("at 3 o'clock") | Native | 세 시 |
| Counting cups/people/things | Native | 사과 두 개 |
The classic self-check: 시 (hour) is native, 분 (minute) is Sino. 한 시 십 분 — "at 1:10" uses both systems in one phrase. Getting that right once means you've internalized the whole split.
Counters: the words that sit after native numbers#
Native numbers almost always appear with a counter noun attached, like "two pieces of cake." Common ones:
| Counter | Counts | Example |
|---|---|---|
| 개 | objects | 사과 두 개 (two apples) |
| 명 | people | 친구 세 명 (three friends) |
| 잔 | cups/glasses | 커피 한 잔 (one cup of coffee) |
| 병 | bottles | 맥주 두 병 (two bottles of beer) |
| 시 | hours (of the clock) | 두 시 (2 o'clock) |
| 시간 | hours (duration) | 두 시간 (two hours) |
| 번 | times | 두 번 (twice) |
| 살 | age | 서른 살 (30 years old) |
Careful with the classic contrast:
두 시 — "2 o'clock" (a point in time) 두 시간 — "2 hours" (a span of time)
And for "how many," the question uses native: 몇 개? (how many items), 몇 명? (how many people).
A few pronunciation wrinkles#
- 1, 2, 3, 4 before counters have fixed short forms: 하나→한, 둘→두, 셋→세, 넷→네. 한 명, 두 개, 세 잔, 네 병.
- Money's zero is 공: 010 = 공일공; 2,000 = 이천.
Note: in counters like 명 and 시, 1–4 are always 한/두/세/네 (한 명, 두 시). This one cheat-sheet covers most of what you'll actually speak.
Common learner mistakes#
| Mistake | Fix |
|---|---|
| 나는 25세 → using Sino age | Age uses native: 스물다섯 살 |
| 세 시 십오분 → mixing fine, remember which part | 시 native, 분 Sino |
| 하나 개 instead of 한 개 | 1–4 drop final consonant before counters |
| Counting money with native | Money is always Sino (천, 만) |
| "몇" with a random system | 몇 is neutral — attach the right counter |
Practice: read these out loud#
- 커피 한 잔 주세요. — one cup of coffee
- 친구 두 명이에요. — two friends
- 오천 원이에요. — it's 5,000 won (price)
- 지금 두 시 십 분이에요. — it's 2:10 now
- 만나서 반가워요 — not a number, but you now hear the 음 in there
Numbers unlock the practical layer of Korean — time and dates run entirely on this split, and ordering at a cafe becomes effortless with 한 잔/한 개. If the -요 endings on those examples felt familiar, you met them in Part 3 on politeness.
