Cut out a circle with the largest area from a square iron sheet with an area of 16 square decimeters. What is the area of the remaining iron sheet?
从一张面积是16平方分米正方形铁皮中，剪下一个面积为最大的圆，剩下铁皮的面积是多少平方分米？
<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>

<result>3.44</result>