A 6-meter-long wire, first use up (5/6) meters, and then use up (5/6) meters, how many meters are left.
一根6米长的电线，先用去(5/6)，又用去(5/6)米，还剩多少米．
<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">6 * (5/6)</gadget>
<output>5</output>

<gadget id="calculator">6 - 5 - (5/6)</gadget>
<output>1/6 = around 0.166667</output>

<result>1/6 = around 0.166667</result>