A copper wire is 10 meters long, and 6 meters are used up, what percentage is left?
一根铜丝长10米，用去6米，还剩下百分之几？
<gadget id="calculator">10 - 6</gadget>
<output>4</output>

<gadget id="calculator">4 / 10</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>