Cut the largest circle on a piece of rectangular paper with a length of 4 cm and a width of 2 cm. What is the area of the circle in the area of the rectangle?
在一张长4cm，宽2cm的长方形纸上剪一个最大的圆形，圆形的面积占这个长方形面积的多少．
<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">1 ** 2</gadget>
<output>1</output>

<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">3.14 * (1/8)</gadget>
<output>0.3925</output>

<result>0.3925</result>