Days, months and dates

The week is named after the elements

Each day is an element plus ようび: げつ moon, か fire, すい water, もく wood, きん metal, ど earth, にち sun. Sunday and Monday are the sun and the moon, and the other five are the classical five elements, which is why the same names appear in Korean and in the planets of many European languages. The question is なんようび.

Months are numbered, dates are learnt

Months are simply the number plus がつ: いちがつ is January and じゅうにがつ December, with しがつ, しちがつ and くがつ keeping their old readings. Dates are the hard part: the first ten days and the twentieth come from the old native series and must be learnt one by one – ついたち, ふつか, みっか, よっか, いつか, むいか, なのか, ようか, ここのか, とおか, and はつか for the twentieth. Everything else is the number plus にち.

きょうはなんようびですかWhat day of the week is it today?

しけんはしがつとおかですThe examination is on the tenth of April.