Xiaohong uses a piece of rectangular hard paper to draw an unfolded picture of a cube carton with a side length of 3 cm. What is the minimum area of this rectangular hard paper in square centimeters?
小红用一张长方形硬纸画一个棱长3厘米的正方体纸盒的展开图，这张长方形硬纸的面积至少是多少平方厘米．
<gadget id="calculator">3 * 4</gadget>
<output>12</output>

<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">12 * 9</gadget>
<output>108</output>

<result>108</result>