The circumference of a cylinder is 31.4 decimeters and its height is 10 decimeters. What is its volume?
一个圆柱的底面周长是31.4分米，高是10分米，它的体积是多少．
<gadget id="calculator">31.4 / 3.14 / 2</gadget>
<output>5</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">3.14 * 25 * 10</gadget>
<output>785</output>

<result>785</result>