A barrel of oil has a total of 30 kilograms, how many kilograms are sold, and (2/3) is left.
一桶油总共有30千克，卖了多少千克，还剩下(2/3)．
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">30 * (1/3)</gadget>
<output>10</output>

<result>10</result>