There is a cylindrical pool with a bottom diameter of 20m and a depth of 4m. Now it is planned to build a cuboid pool with the same volume as the original pool, with a square bottom and a perimeter of 80m. How many meters should be dug deep?
有一个圆柱形水池，底面直径是20m，深4m．现计划修建一个和原水池容积相等，底面是正方形，周长是80m的长方体水池，应挖几米深？
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">3.14 * 100 * 4</gadget>
<output>1_256</output>

<gadget id="calculator">80 / 4</gadget>
<output>20</output>

<gadget id="calculator">20 * 20</gadget>
<output>400</output>

<gadget id="calculator">1_256 / 400</gadget>
<output>157/50 = around 3.14</output>

<result>157/50 = around 3.14</result>