The diameter of a circle is 5 meters, what is the area in square meters?
一个圆的直径是5米，面积是多少平方米．
<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">(5/2) ** 2</gadget>
<output>25/4 = around 6.25</output>

<gadget id="calculator">3.14 * (25/4)</gadget>
<output>19.625</output>

<result>19.625</result>