Part of the Korean Whodunit grammar series · Korean reviewed by native speakers
Korean has two complete number systems, and choosing the wrong one instantly marks a sentence as off. Native Korean numbers count things; Sino-Korean numbers label them. Learn which is which and you will never miscount — or miss when someone else does.
Native Korean numbers (하나, 둘, 셋…) count objects, people, age, and the hour. Sino-Korean numbers (일, 이, 삼…), borrowed from Chinese, handle minutes, money, dates, phone numbers, and anything above roughly one hundred.
three apples — native Korean 셋 becomes 세 before a counter.
3,000 won — money always uses Sino-Korean.
A quick test: if you are counting how many, reach for native Korean. If you are reading a label — a price, a date, a room number — reach for Sino-Korean.
Korean clock time is the classic trap: the hour is native Korean, the minutes are Sino-Korean. 세 시 삼십 분 means "3:30" — 세 (native) for the hour, 삼십 (Sino) for the minutes. Mixing them up is the single most common learner tell.
A suspect who gives an alibi time as 세 시 세 십 분 — native numbers for the minutes — has not just made a cute mistake. A native speaker never says it that way. In a written statement, that error can mark the whole account as composed by someone who does not actually speak the language they claim.
Native numbers rarely stand alone; they pair with a counter that names what is being counted — 개 for objects, 명 for people, 마리 for animals, 잔 for cupfuls. The number changes shape before a counter: 하나→한, 둘→두, 셋→세, 넷→네.
four people — 넷 becomes 네 before the counter 명.
Numbers carry facts: times, amounts, counts. In a mystery, a number in the wrong system is a crack in the story.
Several Korean Whodunit cases turn on a detail of time or quantity. Test your number sense against the evidence. Free, no sign-up.
Browse the Cases →