A cylinder with a radius of 2 cm is a square, what is its volume?
一个圆柱的半径是2厘米，侧面展开是一个正方形，它的体积是多少？
<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">2 * 3.14 * 2</gadget>
<output>12.56</output>

<gadget id="calculator">3.14 * 4 * 12.56</gadget>
<output>157.7536</output>

<result>157.7536</result>