There is an iron wire, all (1/4) of it was used the first time, (1/4) m was used the second time, and all (1/4) was left useless. How long is this iron wire in meters?
有一根铁丝，第一次用去了全部的(1/4)，第二次用去了(1/4)m，还剩全部的(1/4)没有用，这根铁丝长多少米？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4) - (1/4)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/4) / (1/2)</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>