A cylindrical granary with a base diameter of 4 meters and a height of 2.5 meters. Now it is necessary to paint its inner wall and bottom surface with waterproof paint, which costs 1.5 yuan per square meter of paint. How much does it cost to buy paint?
一个圆柱形粮仓，底面直径为4米，高2.5米．现要将它的内壁和底面刷上防水涂料，每平方米涂料需1.5元．购涂料共需多少元？
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<gadget id="calculator">3.14 * 4 * 2.5</gadget>
<output>31.4</output>

<gadget id="calculator">12.56 + 31.4</gadget>
<output>43.96</output>

<gadget id="calculator">1.5 * 43.96</gadget>
<output>65.94</output>

<result>65.94</result>