億(おく)

おく

number, noun

one hundred million; 100,000,000

See also: 兆(ちょう) (one trillion), 万(まん) (ten thousand)

1. one hundred million; 100,000,000

The Japanese number unit equal to one hundred million (10^8). Part of the Japanese numeral system where large numbers are grouped by ten-thousands: 万(まん) (10,000), 億(おく) (100,000,000), 兆(ちょう) (1,000,000,000,000).

世界(せかい)の人口(じんこう)は80億(おく)人(にん)を超(こ)えた。

The world population has exceeded 8 billion.

その会社(かいしゃ)の売上(うりあげ)は年間(ねんかん)10億(おく)円(えん)を超(こ)える。

That company's annual sales exceed one billion yen.

何億年(なんおくねん)も前(まえ)に恐竜(きょうりゅう)は地球(ちきゅう)に生(い)きていた。

Hundreds of millions of years ago, dinosaurs lived on Earth.

Usage

Japanese groups large numbers by ten-thousands, not by thousands as in English. This means 1億(おく) = 10,000 × 10,000 = 100,000,000. When converting between Japanese and English number expressions, this shift is a common source of confusion.

Number scale

万(まん) = 10,000
億(おく) = 100,000,000 (= 10,000万(まん))
兆(ちょう) = 1,000,000,000,000 (= 10,000億(おく))

Common collocations

1億円(おくえん) (100 million yen)
数億円(すうおくえん) (several hundred million yen)
何億(なんおく)もの〜 (hundreds of millions of ~)

general

Added 2026.3.19 18:16 · Revised 2026.9.2 13:01

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