Build numbers from a few parts

Japanese builds numbers, it does not store words. One to ten: いち, に, さん, よん, ご, ろく, なな, はち, きゅう, じゅう. Eleven is ten-one: じゅういち. Twenty is two-ten: にじゅう. Twenty-five is two-ten-five: にじゅうご. With those ten words you reach 99.

A hundred is ひゃく, a thousand is せん — on their own, with no いち in front. にひゃく is 200, さんぜん 3000. A few sounds change where number and word meet: さんびゃく, ろっぴゃく, はっぴゃく, さんぜん, はっせん. That is pronunciation, not new words.

よん, なな and きゅう also have a second form — し, しち, く — used in some places, for example the clock: よじ, しちじ, くじ. Count with よん, なな, きゅう; learn the other forms where they turn up.

A number rarely stands alone. After it comes a word that says what is counted: えん for yen, さい for years of age, じ for o'clock, まい for flat things, つ for most other things. And for one to ten things there is a series of its own — ひとつ, ふたつ, みっつ … — that is not built on いち, に, さん.