The water pipes on the outer wall of the building are rectangular parallelepipeds. If each section is 15 decimeters long, the cross section is a rectangle with a length of 1 decimeter and a width of 0.6 decimeters. To make a water pipe, at least how many square decimeters of iron sheet should be used.
楼房外壁用于流水的水管是长方体．如果每节长15分米，横截面是一个长方形，长1分米，宽0.6分米．做一节水管，至少要用铁皮多少平方分米．
<gadget id="calculator">1 * 15</gadget>
<output>15</output>

<gadget id="calculator">0.6 * 15</gadget>
<output>9</output>

<gadget id="calculator">15 + 9</gadget>
<output>24</output>

<gadget id="calculator">24 * 2</gadget>
<output>48</output>

<result>48</result>