Paint a cylinder with a height of 4 meters and a diameter of 4 decimeters at the bottom. What is the area of the paint in square meters?
油漆一根高4米，底面直径是4分米的圆柱，油漆的面积是多少平方米．
<gadget id="calculator">4 / 10</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">3.14 * (2/5) * 4</gadget>
<output>5.024</output>

<result>5.024</result>