Build a cylindrical pool with a depth of 2.5 meters and a bottom diameter of 4 meters. How many square meters does this pool occupy?
修一个深2.5米，底面直径是4米的圆柱形水池，这个水池占地多少平方米．
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">3.14 * 2 * 2</gadget>
<output>12.56</output>

<result>12.56</result>