A square plank with a side length of 10 decimeters is sawn into a circular plank as large as possible. What percentage of the area is reduced?
有一块边长是10分米的正方形木板，把它锯成一个尽可能大的圆板，面积减少了百分之几？
<gadget id="calculator">10 * 10</gadget>
<output>100</output>

<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">3.14 * 25</gadget>
<output>78.5</output>

<gadget id="calculator">100 - 78.5</gadget>
<output>21.5</output>

<gadget id="calculator">21.5 / 100</gadget>
<output>0.215</output>

<result>0.215</result>