If a cylindrical steel pipe with a base area radius of 5 cm and a length of 8 meters is painted with paint, how many square decimeters is the painted area?
把一根底面积半径是5厘米，长是8米的圆柱形钢管涂上油漆，涂油漆的面积是多少平方分米？
<gadget id="calculator">5 / 10</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">8 * 10</gadget>
<output>80</output>

<gadget id="calculator">2 * 3.14 * (1/2) * 80</gadget>
<output>251.2</output>

<result>251.2</result>