Dongfeng Chemical Factory has a cylindrical oil tank filled with oil, the radius of the bottom surface measured from the inside is 4 meters, and the height is 20 meters. If each cubic meter of oil weighs 0.7 tons, how many tons does the oil weigh?
东风化工厂有一个装满石油的圆柱形油罐，从里面量的底面半径是4米，高是20米．如果每立方米石油重0.7吨，这些石油重多少吨？
<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">3.14 * 16 * 20 * 0.7</gadget>
<output>703.36</output>

<result>703.36</result>