일 - one

이 - two

삼 - three

사 - four

오 - five

육 - six

칠 - seven

팔 - eight

구 - nine

십 - ten

To say 15, say (ten) + (five) = (십) + (오) = 십오

To say 30, say (three) + (ten) = (삼) + (십) = 삼십

To say 95, say (nine) + (ten) + (five) = (구) + (십) + (오) = 구십오

♡

And 백 - hundred

To say 107, (hundred) + (seven) = (백) + (칠) = 백칠

To say 120, (hundred) + (two) + (ten) = (백) + [(이) + (십)] = 백이십

To say 400, (four) + (hundred) = (사) + (백) = 사백

To say 688, [(six) + (hundred)] + [(eight) + (ten) + (eight)] = 육백팔십팔

♡

천 - thousand

만 - ten thousand

1054 = 천오십사

And so on.

Remember not to write 10 = 일십, 100 = 일백, 1000 = 일천, 10,000 = 일만. Don't write 일 with it. The word 십, 백, 천, 만 are enough to send the message across.