Cut the largest circle out of a square of cardboard with a side length of 8 cm. What is the area of this circle?
在一块边长为8厘米的正方形硬纸板上剪下一个最大的圆，这个圆的面积是多少．
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">3.14 * 16</gadget>
<output>50.24</output>

<result>50.24</result>