cylindrical paint bucket without a lid has a base radius of 1 decimeter and a height of 2 decimeters. How many square decimeters of iron sheet are needed to make this paint bucket.
一个无盖的圆柱形油漆桶，底面半径是1分米，高是2分米．做这个油漆桶需用铁皮多少平方分米．
<gadget id="calculator">3.14 * 1 * 2 * 2</gadget>
<output>12.56</output>

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

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

<gadget id="calculator">12.56 + 3.14</gadget>
<output>15.7</output>

<result>15.7</result>