piece of iron wire is cut in half and then in half, cut 3 times, and the remaining length is the same as the original length.
一根铁丝一半再一半的剪，剪了3次，最后剩下的长度是原来长度的多少．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">1 * (1/2) * (1/2) * (1/2)</gadget>
<output>1/8 = around 0.125</output>

<result>1/8 = around 0.125</result>