A rectangular iron plate is 10 decimeters long and 8 decimeters wide. Cut out the largest circle from this iron plate. What is the area of this circle in square decimeters?
一张长方形铁板长10分米，宽8分米，在这张铁板中裁下一个最大的圆形，这个圆的面积是多少平方分米．
<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>