The volume of a cuboid oil drum is 18 liters, its length is 25 cm, and its width is 16 cm. To manufacture such an oil drum, how many square meters of iron sheet is needed at least?
一个长方体油桶的容积是18升，它的长是25厘米，宽16厘米，要制造这样一个油桶，至少需要铁皮多少平方米？
<gadget id="calculator">25 * 16</gadget>
<output>400</output>

<gadget id="calculator">1_000 / 400</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">25 * 18 * (5/2)</gadget>
<output>1_125</output>

<gadget id="calculator">16 * 18 * (5/2)</gadget>
<output>720</output>

<gadget id="calculator">400 + 1_125 + 720</gadget>
<output>2_245</output>

<gadget id="calculator">2 / 10_000</gadget>
<output>1/5_000 = around 0.0002</output>

<gadget id="calculator">2_245 * (1/5_000)</gadget>
<output>449/1_000 = around 0.449</output>

<result>449/1_000 = around 0.449</result>