A cylindrical metal bucket without a cover is 0.6 meters high, and the diameter of the bottom surface is 3 decimeters. How many square decimeters of iron should be used to make a pair of such buckets?
一个无盖的圆柱形铁皮水桶高0.6米，量得底面直径是3分米，做一对这样的水桶至少要用铁皮多少平方分米？
<gadget id="calculator">3.14 * 3 * 0.6</gadget>
<output>5.652</output>

<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">(3/2) ** 2</gadget>
<output>9/4 = around 2.25</output>

<gadget id="calculator">3.14 * (9/4)</gadget>
<output>7.065</output>

<gadget id="calculator">5.652 + 7.065</gadget>
<output>12.717</output>

<gadget id="calculator">12.717 * 2</gadget>
<output>25.434</output>

<result>25.434</result>