The kanji 億 おく primarily represents a large number, specifically 100 million. It's used to express incredibly large quantities of things, such as money, people, or any other measurable item. It signifies an immense amount, going far beyond the usual counting scales.

・On-yomi (音読み): オク (oku) ・Kun-yomi (訓読み): None, 億 おく is generally used with its On-yomi.

⚫︎一億円 Translation: One hundred million yen. ⚫︎億万長者 Translation: A millionaire (literally, one hundred million + ten thousand - rich person). ⚫︎人口が数億人 Translation: Population is several hundred million people.

The kanji 億 おく is a 会意形 (かいいけい - combined meaning) character. It is composed of two parts: 人 (ひと - person) and 意 (い - thought/meaning). The original meaning of 億 おく was "to guess" or "to estimate". Later, it came to be used for the very large number representing a multitude of people, reflecting a situation where one cannot count everyone individually but instead must estimate the multitude. Eventually, the meaning evolved, and the character took on its current meaning of 100 million.