How many square centimeters of iron sheet is needed to make a cylindrical bucket without a lid whose bottom diameter and height are both 6 cm.
做一个底面直径和高都是6厘米的圆柱形无盖水桶，需要多少平方厘米的铁皮．
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">3.14 * 9</gadget>
<output>28.26</output>

<gadget id="calculator">3.14 * 6 * 6</gadget>
<output>113.04</output>

<gadget id="calculator">28.26 + 113.04</gadget>
<output>141.3</output>

<result>141.3</result>