In a cylindrical tank with a radius of 10 meters, there is a cuboid iron block with a length of 5 meters and a width of 4 meters. Put it all into the water, and the water level in the bucket will rise by 0.5 meters. Find the height of this piece of iron block ?
在一只半径为10米的圆柱体储水池里，有一只长5米，宽4米的长方体铁块，把它全部放入水中，桶里的水面上升0.5米，求这段铁块的高？
<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<gadget id="calculator">0.5 / 20</gadget>
<output>0.025</output>

<gadget id="calculator">3.14 * 100 * 0.025</gadget>
<output>7.85</output>

<result>7.85</result>