A rope is folded in half three times in a row and each length is measured to be 0.5 meters. How long is this rope in meters?
一根绳子连续对折3次后量得每段长0.5米．这根绳子原来长多少米．
<gadget id="calculator">2 * 2 * 2</gadget>
<output>8</output>

<gadget id="calculator">0.5 * 8</gadget>
<output>4</output>

<result>4</result>