Use rectangular iron sheets with a length of 5 decimeters and a width of 12 decimeters to form a cylindrical exhaust pipe. How many square decimeters of iron sheets are needed to make this exhaust pipe?
用长5分米、宽12分米的长方形铁皮，围成一个圆柱形排气管，做这个排气管需要多少平方分米的铁皮．
<gadget id="calculator">5 * 12</gadget>
<output>60</output>

<result>60</result>