Dong Le participated in the "Environmental Protection Little Guard: Turning Waste into Treasure" activity organized by the school. He made a storage box with discarded cardboard. This storage box is divided into two parts: the inner box and the outer box. After closing the inner box, the The box is 20 cm long, 10 cm wide, and 8 cm high. How much cardboard did you use to make this storage box? (thickness is ignored)
董乐参加学校组织的"环保小卫士之变废为宝"活动，他用废弃的硬纸板制作了一个收纳盒，这个收纳盒分为内盒和外盒两部分，合上内盒后，收纳盒长20厘米，宽10厘米，高8厘米．做这个收纳盒至少用了多少硬纸板？(厚度忽略不计)
<gadget id="calculator">20 * 10</gadget>
<output>200</output>

<gadget id="calculator">20 * 8</gadget>
<output>160</output>

<gadget id="calculator">10 * 8</gadget>
<output>80</output>

<gadget id="calculator">200 + 160 + 80</gadget>
<output>440</output>

<gadget id="calculator">440 * 2</gadget>
<output>880</output>

<result>880</result>