The bottom of a cuboid iron bucket is a square with a side length of 3dm and a height of 0.5m. How many dm**2 iron sheets are needed to make such an open bucket.
一个长方体铁皮承桶底面是一个边长3dm的正方形，高0.5m，做这样一个无盖水桶至少需要多少dm**2的铁皮．
<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>