Expand the side of a cylinder to get a square. The diameter of the base of this cylinder is 5 decimeters. What is the volume of this cylinder?
把一个圆柱的侧面展开得到一个正方形，这个圆柱底面直径是5分米，求这个圆柱的体积是多少？
<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">(5/2) ** 2</gadget>
<output>25/4 = around 6.25</output>

<gadget id="calculator">3.14 * 5</gadget>
<output>15.7</output>

<gadget id="calculator">3.14 * (25/4) * 15.7</gadget>
<output>308.1125</output>

<result>308.1125</result>