How many square decimeters is the remaining area after cutting the two largest discs with a piece of iron sheet with a length of 18dm and a width of 9dm?
用一块长18dm、宽9dm的铁皮切割下两个最大的圆片后，剩下的面积是多少平方分米？
<gadget id="calculator">18 * 9</gadget>
<output>162</output>

<gadget id="calculator">9 / 2</gadget>
<output>9/2 = around 4.5</output>

<gadget id="calculator">(9/2) ** 2</gadget>
<output>81/4 = around 20.25</output>

<gadget id="calculator">3.14 * (81/4) * 2</gadget>
<output>127.17</output>

<gadget id="calculator">162 - 127.17</gadget>
<output>34.83</output>

<result>34.83</result>