In Korea, there are two sets of numbers, first, is native Korean numbers and the second one is the Sino-Korean numbers, which are used more in general.
Native Korean numbers are used for telling time ONLY for hours, amount of hours, amount of months and numbers for age.
Sino-Korean numbers are used for telling time ONLY for minutes and seconds, dates and months of the year, amount of money /currency, maths, measurements, phone numbers, addresses, floor of building and everything else.
If you are unsure which set to use, use Sino-Korean as most Koreans will understand what you mean.
<Sino-Korean>
Zero-yeong [영]
One-il [일]
Two-i [이]
Three-sam [삼]
Four-sa [사]
Five-o [오]
Six-yug [육]
Seven-chil [칠]
Eight-pal [팔]
Nine-gu [구]
Ten-sib [십]
Eleven-sib-il [십일]
Twelve-sib-i [십이]
Thirteen-sibsam [십삼]
Fourteen-sibsa [십사]
Fifteen-sib-o [십오]
Sixteen-sib-yug [십육]
Seventeen-sibchil [십칠]
Eighteen-sibpal [십팔]
Nineteen-sibgu [십구]
Twenty-isib [이십]
Twenty one-isib-il [이십일]
Twenty two-isib-i [이십이]
Twenty three-isibsam [이십삼]
Twenty four-isibsa [이십사]
Twenty five-isib-o [이십오]
Twenty six-isib-yug [이십육]
Twenty seven-isibchil [이십칠]
Twenty eight-isibpal [이십팔]
Twenty nine-isib gu [이십구]
Thirty-samsib [삼십]
Forty-sasib [사십]
Fifty-osib [오십]
Sixty-yugsib [육십]
Seventy-chilsib [칠십]
Eighty-palsib [팔십]
Ninety-gusip [구십]
Hundred-baeg [백]
Thousand-cheon [천]
Ten thousand-man [만]
Hundred thousand-sibman [십만]
Million-beagman [백만]
Billion-sib-eog [십억]
