60% of Korean words are derived from Chinese loan words. Learning to read and write Chinese characters is not necessary for most Korean students given that they are used infrequently in modern Korean texts but learning the sound and meaning of the characters will help you improve your vocabulary similar to how students of English can benefit from learning Latin and Greek roots.

열 십, 전부 십, ten, tenth; complete; perfect (2)
九十 구십 90
四十 사십 40
三十 삼십 30
數十 수십 tens of sth
十月 시월 October
十二月 십이월 December
十二指腸 십이지장 duodenum
十一月 십일월 November
十字架 십자가 cross
五十 오십 fifty
六十 육십 sixty
二十 이십 twenty
七十 칠십 seventy
八十 팔십 80