A ventilation pipe is 50cm long, 10cm wide, and 10cm high. How many square decimeters of iron sheets are needed to make such a pair of ventilation pipes?
一节通风管长50cm，宽10cm，高10cm，做这样的一对通风管至少需要多少平方分米的铁皮？
<gadget id="calculator">50 * 10 * 2</gadget>
<output>1_000</output>

<gadget id="calculator">10 * 10 * 2</gadget>
<output>200</output>

<gadget id="calculator">1_000 + 200</gadget>
<output>1_200</output>

<gadget id="calculator">2 / 100</gadget>
<output>1/50 = around 0.02</output>

<gadget id="calculator">1_200 * (1/50)</gadget>
<output>24</output>

<result>24</result>