cuboid iron bucket without a lid is 2.5 decimeters in length and width and 6 decimeters in depth. How many square decimeters of iron sheets are needed to make a pair of such buckets?
一个长方体的无盖铁皮水桶，长和宽都是2.5分米，深6分米．做一对这样的水桶，至少需要多少平方分米铁皮？
<gadget id="calculator">2.5 * 2.5</gadget>
<output>6.25</output>

<gadget id="calculator">2.5 * 6 * 4</gadget>
<output>60</output>

<gadget id="calculator">6.25 + 60</gadget>
<output>66.25</output>

<gadget id="calculator">66.25 * 2</gadget>
<output>132.5</output>

<result>132.5</result>