A cylindrical oil drum filled with oil, with a base radius of 30 cm and a height of 60 cm, is used to lift the oil out of a conical container with a base radius of 15 cm and a height of 20 cm. How many times should it be lifted at least?
一个装满油的圆柱形油桶，底面半径是30厘米，高60厘米，用一个底面半径是15厘米，高20厘米的圆锥形容器向外提油，至少要提多少次才能全部提完？
<gadget id="calculator">30 ** 2</gadget>
<output>900</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">15 ** 2</gadget>
<output>225</output>

<gadget id="calculator">(1/3) * 3.14 * 225 * 20</gadget>
<output>4_710</output>

<gadget id="calculator">60 / 4_710</gadget>
<output>2/157 = around 0.012739</output>

<gadget id="calculator">3.14 * 900 * (2/157)</gadget>
<output>36</output>

<result>36</result>