piece of iron wire is 3 meters long, (1/2) is used for the first time, and (1/2) is used for the second time, how many meters are left?
一根铁丝长3米，第一次用去(1/2)，第二次用去(1/2)米，还剩多少米．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">3 * (1/2)</gadget>
<output>3/2 = around 1.5</output>

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

<result>1</result>