A 7-meter-long rope is used to wrap 2 times around the pillar in the hall, and there is still 0.72 meters left. What is the area occupied by this pillar?
用一根长7米的绳子绕大厅柱子2圈还剩0.72米，这根柱子的占地面积是多少？
<gadget id="calculator">7 - 0.72</gadget>
<output>6.28</output>

<gadget id="calculator">6.28 / 2 / 3.14 / 2</gadget>
<output>0.5</output>

<gadget id="calculator">0.5 ** 2</gadget>
<output>0.25</output>

<gadget id="calculator">3.14 * 0.25</gadget>
<output>0.785</output>

<result>0.785</result>