Cut a circular piece of paper with a diameter of 8 cm into the largest square, what is the area of the cut part in square centimeters?
把一张直径是8cm的圆形纸片剪成一个最大的正方形，剪去部分的面积是多少平方厘米．
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">3.14 * 16</gadget>
<output>50.24</output>

<gadget id="calculator">8 * 4</gadget>
<output>32</output>

<gadget id="calculator">50.24 - 32</gadget>
<output>18.24</output>

<result>18.24</result>