There is a cylindrical fish tank with an inner diameter of 4m and a height of 2m in the lobby of a certain hotel. A cylindrical stone with a bottom diameter of 2m and a height of 1.6m is placed in the fish tank. How much water can this tank hold?
某酒店大堂里有一个内直径4m、高2m的圆柱形鱼缸，鱼缸里面放了一块底面直径2m、高1.6m的圆柱形石头．这个鱼缸最多能装多少水？
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4 * 2</gadget>
<output>25.12</output>

<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">1 ** 2</gadget>
<output>1</output>

<gadget id="calculator">3.14 * 1 * 1.6</gadget>
<output>5.024</output>

<gadget id="calculator">25.12 - 5.024</gadget>
<output>20.096</output>

<result>20.096</result>