Draw the largest circle in a square with a perimeter of 8 cm, what is the area of the remaining part?
在一个周长是8cm的正方形内画一个最大的圆，剩下的部分的面积占多少．
<gadget id="calculator">8 / 4</gadget>
<output>2</output>

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

<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">1 ** 2</gadget>
<output>1</output>

<gadget id="calculator">3.14 * 1</gadget>
<output>3.14</output>

<gadget id="calculator">4 - 3.14</gadget>
<output>0.86</output>

<gadget id="calculator">0.86 / 4</gadget>
<output>0.215</output>

<result>0.215</result>