The table below shows the “pure Korean” numbers. They are used mostly for counting.


To put together numbers like "17" or "35" you just write the tens number followed
by the ones number. Thus,
17 = 열일곱
35 = 서른다섯
Note: when they precede a “classifier” (such as the word for “o’clock” when telling time), numbers ending in digits 14 and the number 20 change as follows:
하나
becomes 한
둘
becomes 두
셋
becomes 세
넷
becomes 네
, and
스물
becomes 스무