To build a biogas digester with a bottom diameter of 35m and a depth of 2m, how many cubic meters of soil should be excavated?
修建一个底面直径是35m，深2m的沼气池，挖出土多少立方米？
<gadget id="calculator">35 / 2</gadget>
<output>35/2 = around 17.5</output>

<gadget id="calculator">(35/2) ** 2</gadget>
<output>1_225/4 = around 306.25</output>

<gadget id="calculator">3.14 * (1_225/4) * 2</gadget>
<output>1_923.25</output>

<result>1_923.25</result>