A piece of iron wire is cut in half each time, and after three cuts, there is still 3.5 meters left. How long is this wire?
一根铁丝每次剪去一半，剪了三次还剩3.5米．这根铁丝原来有多长？
<gadget id="calculator">3.5 * 2 * 2 * 2</gadget>
<output>28</output>

<result>28</result>