About counting dates in Japanese

There are two ways to say the number one, one is ついたち and the other is いちにち. If you use the latter one, the day and the number one are the same.

The rest of the days and numbers correspond to each other, e.g., the eleventh day (じゅういちにち), the twenty-fourth day (にじゅうよっか)

Additionally there is no corresponding date for more than 31 days.

Additionally, the addition of かん, as mentioned above, is used to indicate the total amount of time in a few days. It doesn't mean that you have to add かん to indicate a few days, for example: この仕事、十日以内に终わらせてください.