The length, width, and height of an anhydrous ornamental fish tank are 46cm, 25cm, and 28cm respectively. There is a fake stone mountain with a height of 28cm and a volume of 4200 cubic centimeters inside. , so at least how long will it take to completely submerge the fake rock mountain?
一个无水观赏鱼缸长、宽、高分别是46cm、25cm、28cm，在里面方有一块高为28cm、体积为4200立方厘米假石山，如果水管以每分钟8立方分米的流量向鱼缸内注水，那么至少需要多长时间才能将假石山完全淹没？
<gadget id="calculator">46 * 25 * 28</gadget>
<output>32_200</output>

<gadget id="calculator">32_200 - 4_200</gadget>
<output>28_000</output>

<gadget id="calculator">8 * 1_000</gadget>
<output>8_000</output>

<gadget id="calculator">28_000 / 8_000</gadget>
<output>7/2 = around 3.5</output>

<result>7/2 = around 3.5</result>