To make a pair of rectangular buckets without a cover, the bottom surface is a square with a side length of 3 decimeters and a height of 4 decimeters, how much iron sheet should be used at least?
做一对无盖的长方形水桶，底面是边长3分米的正方形，高4分米，至少用多少铁皮？
<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">3 * 4 * 4</gadget>
<output>48</output>

<gadget id="calculator">9 + 48</gadget>
<output>57</output>

<gadget id="calculator">57 * 2</gadget>
<output>114</output>

<result>114</result>