Use 18 cubes whose edge length is 1 cm to form a cuboid with the smallest surface area. What is its surface area?
用18个棱长是1厘米的正方体拼成一个表面积最小的长方体，它的表面积是多少．
<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">9 + 6 + 6</gadget>
<output>21</output>

<gadget id="calculator">21 * 2</gadget>
<output>42</output>

<result>42</result>