A cylindrical water pipe has a ground radius of 4cm and a length of 4m. It is necessary to paint a layer of paint on its outer surface. What is the area to be painted in square centimeters?
一根圆柱形水管，它的地面半径是4cm，长是4m，要在它的外表面涂上一层油漆，要涂油漆的面积是多少平方厘米？
<gadget id="calculator">2 * 3.14 * 0.8 * 4</gadget>
<output>20.096</output>

<result>20.096</result>