Make a cube glass water tank (without cover) with side length 0.4m. What is the minimum square meter of glass needed to make this sink?
做一个正方体玻璃水槽(无盖)，棱长0.4m．制作这个水槽至少需要玻璃多少平方米？
<gadget id="calculator">0.4 * 0.4 * 5</gadget>
<output>0.8</output>

<result>0.8</result>