A cylindrical water tank has a bottom diameter of 2 decimeters and a height of 3 decimeters. How many square decimeters of iron sheet are needed to make this tank without a cover?
一个圆柱形水箱，底面直径是2分米，高是3分米，制作这个无盖水箱需要铁皮多少平方分米．
<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">1 ** 2</gadget>
<output>1</output>

<gadget id="calculator">3.14 * 1</gadget>
<output>3.14</output>

<gadget id="calculator">3.14 * 2 * 3</gadget>
<output>18.84</output>

<gadget id="calculator">3.14 + 18.84</gadget>
<output>21.98</output>

<result>21.98</result>