Japanese/Lessons/Days

Counting the days of the month is really pretty simple — with a few exceptions. The first ten days generally follow the "native Japanese" counting stems. After the tenth of the month, all but the 14th, 20th and 24th follow the more basic Chinese-derived counting stems.

The first of the month is an exception, and simply must be memorized as such:
 * １日　ついたち

The second through tenth of the month follow the same native Japanese counting stems as used when counting generic items (つ,　つ,　つ, つ) or people. The ending "〜か" is simply one of the readings for the character for "日".
 * ２日　ふつか
 * ３日　みっか
 * ４日　よっか
 * ５日　いつか
 * ６日　むいか
 * ７日　なのか
 * ８日　ようか
 * ９日　ここのか
 * １０日　とおか

The rest of the days of the month, generally follow the normal pattern using the counters "いち", "に", "さん", etc., and the ending "〜か" is replaced with "〜にち". The numbers 14 and 24 use "〜よっか", not "〜よんにち" as one might assume from the pattern, and 20 uses "はつか", not "にじゅうにち".

Periods of days

 * "前" (まえ), which generally means "before" or "in front of", is used to indicate an amount of time ago.
 * "〜間" (かん) is used to indicate a length of time. It is usually dropped when unambiguous.

When periods of time are expressed in terms of "nights", the counter "泊" (はく) which means "night" or "overnight" in the context of staying somewhere, is affixed to the normal "いち", "に", "さん", etc.

The same character is also used for the word "泊まる" (とまる) which means "to stay" or "to stay over". As in English, this can be combined with "days", which is then read as the days of the week ("いっか", "ふつか", "みっか", "よっか, etc.).