To make an iron box without a cover with a length of 1m, a width of 5dm, and a height of 8dm, how many square meters of iron sheet are needed at least?
做一个长1m，宽5dm，高8dm的无盖铁箱，至少需要多少平方米铁皮？
<gadget id="calculator">5 / 10</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 * (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">8 / 10</gadget>
<output>4/5 = around 0.8</output>

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

<gadget id="calculator">(1/2) * (4/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(1/2) + (4/5) + (2/5)</gadget>
<output>17/10 = around 1.7</output>

<gadget id="calculator">(17/10) * 2</gadget>
<output>17/5 = around 3.4</output>

<result>17/5 = around 3.4</result>