A circular pool has a base radius of 2 meters. Pour 6.28 cubic meters of water into the pool, how deep is the water?
一个圆形水池，底面半径是2米．往池里灌进6.28立方米的水，水深多少米？
<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<gadget id="calculator">6.28 / 12.56</gadget>
<output>0.5</output>

<result>0.5</result>