noun
irreducible fraction; fraction in lowest terms
Mathematical term for a fraction whose numerator and denominator are coprime (i.e., cannot be simplified further).
2/3は既約分数ですが、4/6は既約分数ではありません。
2/3 is an irreducible fraction, but 4/6 is not.
分数を既約分数に直すには、分子と分母を最大公約数で割ります。
To reduce a fraction to its lowest terms, divide the numerator and denominator by their greatest common divisor.