Bilangan rasional

Natural numbers ($\mathbb {Q}$, quotient = hasil bagi)

$\mathbb {Q} =\lbrace {\frac {m}{n}}:m,n\in \mathbb {Z} ,n\neq 0\rbrace$

$\mathbb {Z}$ : Bilangan bulat

Desimal

Bilangan rasional memiliki karakteristik desimal berulang.

${\frac {1}{9}}=0,11111...=O,{\bar {1}}{\frac {1}{2}}=0,50000...=O,5{\bar {0}}{\frac {3}{7}}=0,272727...=O,{\bar {27}}$