Make a cuboid iron box without a cover, 0.6 meters long, 0.35 meters wide, and 0.4 meters high. At least how many square meters of iron sheet is needed?
做一个不带盖的长方体铁盒，长0.6米，宽0.35米，高0.4米．至少需要多少平方米铁皮？
<gadget id="calculator">0.6 * 0.35</gadget>
<output>0.21</output>

<gadget id="calculator">0.6 * 0.4 * 2</gadget>
<output>0.48</output>

<gadget id="calculator">0.35 * 0.4 * 2</gadget>
<output>0.28</output>

<gadget id="calculator">0.21 + 0.48 + 0.28</gadget>
<output>0.97</output>

<result>0.97</result>