A cylindrical tin oil barrel with a bottom diameter of 6 decimeters and a height of 1 meter contains gasoline 5 decimeters deep. Ask how many liters of gasoline are needed to fill the oil tank at most? 6 points.
一个底面直径是6分米，高为l米的圆柱形铁皮油桶，桶内装有5分米深的汽油．问最多还需要装多少升汽油就可以将油桶注满？6分．
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">3.14 * 9 * 5</gadget>
<output>141.3</output>

<result>141.3</result>