Build a circular pond to raise fish. The height of the pond is 1 meter, the inner diameter of the pond is 12 meters, and the thickness of the pond wall is 5 decimeters. How much concrete is needed to build such a fish pond?
修一个圆形水池养鱼，池高1米，水池的内部直径是12米，池壁厚5分米，那么修建一个这样的养鱼池需要多少混泥土？
<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">5 / 10</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">6 + (1/2)</gadget>
<output>13/2 = around 6.5</output>

<gadget id="calculator">(13/2) ** 2</gadget>
<output>169/4 = around 42.25</output>

<gadget id="calculator">3.14 * (169/4)</gadget>
<output>132.665</output>

<gadget id="calculator">6 ** 2</gadget>
<output>36</output>

<gadget id="calculator">3.14 * 36</gadget>
<output>113.04</output>

<gadget id="calculator">132.665 - 113.04</gadget>
<output>19.625</output>

<gadget id="calculator">19.625 * 1</gadget>
<output>19.625</output>

<result>19.625</result>