you can use 일,이,삼,사 to read a numeral. you can use 하나,둘,셋,넷 to count the things. 하나 둘 셋 넷 -> noun 한 두 세 네 -> adjective 다섯, 여섯, ... are same between two forms. 하나(1) 둘(2) 셋(3) 넷(4) 다섯(5) 여섯(6) 일곱(7) 여덟(8) 아홉(9) 열(10) 스물(20) 서른(30) 마흔(40) 쉰(50) 예순(60) 일흔(70) 여든(80) 아흔(90) ... 백, 이백, .. are as same as 일,이,삼,사..... forms to say your age, ex) 내 나이는 스물넷(살)이야. I'm 24 years old. to count a number of times?! -> 팔굽혀펴기 열개 실시! 하나, 둘, 셋, ... Start doing push-ups! one, two, three, ... to say how many things?! -> 탁자에 사과가 다섯(개) 있다. There are five apples on the table. 종이가 여덟(장) 있다. There are eight pieces of paper?! 살, 개, 장 are... the count unit?!

When you see numbers and say them, you can read like 일, 이, 삼, 사... But there're some exceptions for this. When you say your age or others' you should say 한 살, 두 살, 세 살... And the other exception, it's 12:41 am right now. I'd say 열두 시 사십 일 분. 4:20pm 네 시 이십 분 I hope you don't mind if I correct a little your Korean, Soonoh. 스물 네 살 is spelt right and the spacing of it is correct. It's right to say 나 스물 넷이야. But I don't think I could say 종이가 여덟 있다 which sounds a little bit awkward. I'd say 종이가 여덟 장 있다 instead. (한, 두, 세...)개 : Counting to things(not alive) in general. 마리 : Counting to animal like dogs, cats, birds 명 : ......people 가지 : referring to kind/sort (of) 장 : ......pieces of paper 대 : ......electronic goods, transportation like bus, taxi 잔 : ......tea/coffee cups 권 : ......books 상자 : ......boxes 켤레 : ......pairs of shoes 자루 : ......pens, pencils 팩 : ......cartons of milk etc Here are a couple of colloquial expressions. 하나도 안 했다 I didn't do it at all '한 개도 안 했다' would sound a little emphasized and funny because what they didn't do is uncountable. 거기서 오만 가지 다 해봤다 I've done a lot of things there. Hope this helps.