２４にじゅうよっ日か

に

じゅ

う

よ

っ

か

Meanings

24th day of the month

Only with reading にじゅうよっか

Standard date expression; the reading にじゅうよっか is the only natural one for this meaning.

24 days

Used for a duration of 24 days; the reading にじゅうよっか is standard, while にじゅうよんにち and にじゅうよにち are irregular but sometimes heard.

２５にじゅうご日にち
２５日 (にじゅうごにち) uses the plain にち reading, whereas 二十四日 (にじゅうよっか) for the 24th/24 days uses the irregular よっか pattern, so the two are easy to confuse when reading dates aloud.

Compound of 二十四 (にじゅうよん, twenty-four) + 日 (か/にち, day). The reading にじゅうよっか is a euphonic change from にじゅうよんか.