cuboid tin bucket without a cover is 3 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?
一个无盖的长方体铁皮水桶，长和宽都是3分米，深6分米．做一对这样的水桶，至少需要多少平方分米的铁皮？
<gadget id="calculator">6 * 3 * 4</gadget>
<output>72</output>

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

<gadget id="calculator">72 + 9</gadget>
<output>81</output>

<gadget id="calculator">81 * 2</gadget>
<output>162</output>

<result>162</result>