Cut out the largest circle from a square iron sheet with a side length of 4dm, what is the utilization rate of this iron sheet?
从一块边长为4dm的正方形铁皮中剪下一个最大的圆，这块铁皮的利用率是多少？
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<gadget id="calculator">4 * 4</gadget>
<output>16</output>

<gadget id="calculator">12.56 / 16</gadget>
<output>0.785</output>

<gadget id="calculator">100 / 100</gadget>
<output>1</output>

<gadget id="calculator">0.785 * 1</gadget>
<output>0.785</output>

<result>0.785</result>