A cylindrical pool with an inner diameter of 8 meters and a depth of 2 meters. There are 4 identical water inlet pipes on the pool. Each tube can inject 6.28 cubic meters of water per hour. When the four pipes are put together, the pool can be filled in a few hours. ?
一个圆柱形水池，它的内直径是8米，深2米，池上装有4个同样的进水管，每个管每小时可以注入水6.28立方米，四管齐放，几小时可以注满水池？
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">3.14 * 16 * 2</gadget>
<output>100.48</output>

<gadget id="calculator">6.28 * 4</gadget>
<output>25.12</output>

<gadget id="calculator">100.48 / 25.12</gadget>
<output>4</output>

<result>4</result>