To make a cylindrical tin bucket without a cover, the height is 30cm, and the bottom diameter is 20cm. How many square decimeters of tin should be used to make this bucket?
做一个无盖的圆柱形铁皮水桶，高30cm，底面直径20cm，做这个水桶至少要用多少平方分米的铁皮？
<gadget id="calculator">3.14 * 20 * 30</gadget>
<output>1_884</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">3.14 * 100</gadget>
<output>314</output>

<gadget id="calculator">1_884 + 314</gadget>
<output>2_198</output>

<gadget id="calculator">2_198 / 100</gadget>
<output>1_099/50 = around 21.98</output>

<result>1_099/50 = around 21.98</result>