The diameter of a circle is 1.6dm, what is the area of the circle?
一个圆的直径是1.6dm，这个圆的面积是多少．
<gadget id="calculator">1.6 / 2</gadget>
<output>0.8</output>

<gadget id="calculator">0.8 ** 2</gadget>
<output>0.64</output>

<gadget id="calculator">3.14 * 0.64</gadget>
<output>2.0096</output>

<result>2.0096</result>