How many square decimeters of cardboard should be prepared to make a cube carton without a cover with a side length of 3 decimeters.
做一个棱长3分米的无盖正方体纸盒，至需要准备多少平方分米的硬纸板．
<gadget id="calculator">3 * 3 * 5</gadget>
<output>45</output>

<result>45</result>