The perimeter of the cross-section of a rectangular parallelepiped ventilation pipe is 12.5dm, and the length is 4m. How much iron sheet should be used to make this section of ventilation pipe in m**2.
一节长方体通风管横截面的周长是12.5dm，长4m，制作这一节通风管要用铁皮多少m**2．
<gadget id="calculator">12.5 / 10</gadget>
<output>1.25</output>

<gadget id="calculator">1.25 * 4</gadget>
<output>5</output>

<result>5</result>