A cuboid tin bucket without a cover has a bottom of 3 decimeters square and a bucket height of 0.5 meters. How many square decimeters of iron must be used to make such a bucket?
一个无盖的长方体铁皮水桶，底面是3分米的正方形，桶高0.5米，做这样的水桶至少要用多少平方分米铁皮？
<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">0.5 * 10</gadget>
<output>5</output>

<gadget id="calculator">3 * 5 * 4</gadget>
<output>60</output>

<gadget id="calculator">9 + 60</gadget>
<output>69</output>

<result>69</result>