The diameter of the base of a cylinder is 4 cm, and the ratio of diameter to height is 2:5. What is the volume of the cylinder?
一个圆柱底面直径是4厘米，直径与高的比是2：5，这个圆柱的体积是多少？
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

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

<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">4 * (5/2)</gadget>
<output>10</output>

<gadget id="calculator">3.14 * 4 * 10</gadget>
<output>125.6</output>

<result>125.6</result>