cylindrical oil barrel has a base radius of 2 decimeters measured from the inside and a height of 5 decimeters. What is its volume in liters?
一个圆柱形油桶，从里面量底面半径为2分米，高为5分米．它的容积是多少升？
<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4 * 5</gadget>
<output>62.8</output>

<result>62.8</result>