A cylinder has a base radius of 5 cm and a height of 10 cm, what is the circumference of the base in cm?
一个圆柱的底面半径是5厘米，高是10厘米，它在底面周长是多少厘米．
<gadget id="calculator">3.14 * 5 * 2</gadget>
<output>31.4</output>

<result>31.4</result>