A colored ribbon is (1/2) meter long, if (1/3) meter is used up, how many meters are left
一根彩带长(1/2)米，用去(1/3)米，还剩多少米
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/2) - (1/3)</gadget>
<output>1/6 = around 0.166667</output>

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