既き約やく分ぶん数すう

き

や

く

ぶ

ん

す

う

Meanings

irreducible fraction; fraction in lowest terms

Mathematical term for a fraction whose numerator and denominator are coprime (i.e., cannot be simplified further).

、

六ろく

分ぶん

の

四よん

は

既き

約やく

分ぶん

数すう

で

は

あり

ませ

ん

。

Two-thirds is an irreducible fraction, but four-sixths is not.

分ぶん数すうを既き約やく分ぶん数すうに直なおすには、分ぶん子しと分ぶん母ぼを最さい大だい公こう約やく数すうで割わります。

To reduce a fraction to its lowest terms, divide the numerator and denominator by their greatest common divisor.

約やく分ぶん
約分 is the process of reducing a fraction, while 既約分数 is the resulting irreducible fraction.
分ぶん数すう
分数 is a general term for any fraction; 既約分数 specifically refers to a fraction in its simplest form.

Compound of 既約 (kiyaku, 'irreducible') + 分数 (bunsū, 'fraction'). The term is a direct calque from Western mathematical terminology.