A cuboid fish tank without a cover is 0.4m long, 0.4m wide, and 0.2m deep. How many square meters of glass should be used to make this fish tank?
一个无盖的长方体鱼缸，长0.4m，宽0.4m，深0.2m，做这个鱼缸至少要用玻璃多少平方米？
<gadget id="calculator">0.4 * 0.4</gadget>
<output>0.16</output>

<gadget id="calculator">0.4 * 0.2 * 2</gadget>
<output>0.16</output>

<gadget id="calculator">0.16 + 0.16 + 0.16</gadget>
<output>0.48</output>

<result>0.48</result>