one's 20s; twenties
Refers to the age range 20–29 or people in that age group. Often used with possessive or descriptive phrases.
He started his business in his twenties.
This survey targets women in their twenties.
Refers to one's thirties (30–39), the next decade after 二十代.
Kanji spelling; standard in formal or literary contexts.
Common numeric spelling; widely used in charts, articles, and casual writing.
Compound of 二十 (twenty) and 代 (generation, era, range), literally 'the twenty range'.