How many square centimeters of cardboard is needed to make a cube without a cover with a side length of 20 cm?
做一个棱长为20厘米的正方体无盖纸盒，做这个纸盒至少需要硬纸板多少平方厘米？
<gadget id="calculator">20 * 20 * 5</gadget>
<output>2_000</output>

<result>2_000</result>