What is the area of a circular piece of iron with a radius of 2 decimeters?
一块圆形铁片，半径2分米，面积是多少平方分米？
<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<result>12.56</result>