Cut off two equal and as large circles as possible from a square iron sheet with a side length of 6 decimeters, what is the area of the remaining iron sheet in square decimeters?
在一块边长6分米的正方形铁皮上剪去两个相等并尽可能大的圆，剩下的铁皮面积是多少平方分米？
<gadget id="calculator">6 * 6</gadget>
<output>36</output>

<gadget id="calculator">6 / 2 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">(3/2) ** 2</gadget>
<output>9/4 = around 2.25</output>

<gadget id="calculator">3.14 * (9/4) * 2</gadget>
<output>14.13</output>

<gadget id="calculator">36 - 14.13</gadget>
<output>21.87</output>

<result>21.87</result>