千せん分ぶん

noun, noun which may take the genitive case particle 'no'

division by 1000; one-thousandth

Used in mathematical or technical contexts to express a fraction or division into 1000 parts. Often appears in compounds like 千分率 (per mille).

• 千せん分ぶんの一いちの確かく率りつで当あたる。

  It hits with a probability of one in a thousand.

• 千せん分ぶん率りつはパーミルとも呼よばれる。

  The rate per thousand is also called permille.