If the circumference of the base of a cylinder is 12.56 meters, what is the area of its base?
一个圆柱的底面周长是12.56米，它的底面积是多少．
<gadget id="calculator">12.56 / 3.14 / 2</gadget>
<output>2</output>

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

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

<result>12.56</result>