cube cardboard box without a cover, with a side length of 0.8 meters, how many square meters of cardboard should be used to make 200 such cardboard boxes?
一种无盖的正方体硬纸盒，棱长0.8米，制作200个这样的硬纸盒，至少要用硬纸多少平方米？
<gadget id="calculator">0.8 * 0.8 * 5 * 200</gadget>
<output>640</output>

<result>640</result>