Cut the largest circle out of a tin sheet with a length of 8 decimeters and a width of 5 decimeters. What is the area of the trimmed scraps in square decimeters?
在一个长8分米，宽5分米的白铁皮上剪下一个最大的圆，剪去的边角料的面积是多少平方分米？
<gadget id="calculator">8 * 5</gadget>
<output>40</output>

<gadget id="calculator">2.5 ** 2</gadget>
<output>6.25</output>

<gadget id="calculator">3.14 * 6.25</gadget>
<output>19.625</output>

<gadget id="calculator">40 - 19.625</gadget>
<output>20.375</output>

<result>20.375</result>