cuboid carton, 30 cm long, 20 cm wide, and 15 cm high. What is the minimum square centimeter needed to make this carton.
一个长方体纸盒，长30厘米，宽20厘米，高15厘米．做这个纸盒至少要用多少平方厘米．
<gadget id="calculator">30 * 20</gadget>
<output>600</output>

<gadget id="calculator">30 * 15</gadget>
<output>450</output>

<gadget id="calculator">20 * 15</gadget>
<output>300</output>

<gadget id="calculator">600 + 450 + 300</gadget>
<output>1_350</output>

<gadget id="calculator">1_350 * 2</gadget>
<output>2_700</output>

<result>2_700</result>