A rectangular parallelepiped iron box without a cover, the bottom surface is a square with a side length of 3 decimeters and a height of 4 decimeters; how many square decimeters of iron sheet should be used to make this iron box?
一个无盖的长方体铁盒，底面是边长为3分米的正方形，高4分米；做这个铁盒至少要用铁皮多少平方分米？
<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>

<result>57</result>