If a square block with a side length of 4 decimeters is processed into the largest circle, how many percent will the area be reduced from the original? (π is taken as 3.14) (Click on the idea: the diameter of a circle is 4 decimeters).
将一块边长为4分米的正方形木块，加工成一个最大的圆后，面积要比原来减少百分之几？(π取3.14)(思路点击：圆的直径为4分米)．
<gadget id="calculator">4 * 4</gadget>
<output>16</output>

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

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

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<gadget id="calculator">16 - 12.56</gadget>
<output>3.44</output>

<gadget id="calculator">3.44 / 16</gadget>
<output>0.215</output>

<result>0.215</result>