cuboid box is 30 decimeters long, 20 decimeters wide, and 10 decimeters high. How many square decimeters of hard paper should be used to make this carton?
一个长方体纸盒，长30分米，宽20分米，高10分米．做这个纸盒至少要用多少平方分米硬纸？
<gadget id="calculator">30 * 20</gadget>
<output>600</output>

<gadget id="calculator">30 * 10</gadget>
<output>300</output>

<gadget id="calculator">20 * 10</gadget>
<output>200</output>

<gadget id="calculator">600 + 300 + 200</gadget>
<output>1_100</output>

<gadget id="calculator">1_100 * 2</gadget>
<output>2_200</output>

<result>2_200</result>