A cylindrical pool filled with water has a bottom radius of 1 meter. After part of the water is used, the water level drops by 20 cm, and the remaining water is exactly (7/8) of the pool. What is the volume of this pool?
一个注满水的圆柱形水池，底面半径为1米，用去一部分水后，水面下降20厘米，剩下的水正好是这池水的(7/8)．这个水池的容积是多少？
<gadget id="calculator">1 ** 2</gadget>
<output>1</output>

<gadget id="calculator">7 / 8</gadget>
<output>7/8 = around 0.875</output>

<gadget id="calculator">1 - (7/8)</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">20 / (1/8) / 100</gadget>
<output>8/5 = around 1.6</output>

<gadget id="calculator">3.14 * 1 * (8/5)</gadget>
<output>5.024</output>

<result>5.024</result>