How many square meters of glass is needed to make a cube fish tank without a cover with a side length of 4 decimeters?
制作一个无盖的正方体鱼缸，棱长为4分米，至少需要多少平方米的玻璃．
<gadget id="calculator">5 / 100</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">4 * 4 * (1/20)</gadget>
<output>4/5 = around 0.8</output>

<result>4/5 = around 0.8</result>