The school hall has four cylindrical pillars with a base diameter of 8 decimeters and a height of 25 decimeters. To paint these pillars, 0.5 kg of paint is used per square meter. How many kg of paint are needed in total?
学校大厅有4根底面直径8分米，高25分米的圆柱形柱子．要给这些柱子刷上油漆，每平方米用油漆0.5千克，共需要多少千克油漆？
<gadget id="calculator">3.14 * 0.8 * 2.5 * 4</gadget>
<output>25.12</output>

<gadget id="calculator">0.5 * 25.12</gadget>
<output>12.56</output>

<result>12.56</result>