A cylinder has a base radius of 5 cm and its sides are a square. What is the volume of the cylinder?
一个圆柱体的底面半径是5cm，侧面展开是一个正方形，这个圆柱的体积是多少．
<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">2 * 3.14 * 5</gadget>
<output>31.4</output>

<gadget id="calculator">3.14 * 25 * 31.4</gadget>
<output>2_464.9</output>

<result>2_464.9</result>