in a water pipe with an inner diameter of 8 cm. The speed of water flow is 250m per minute, so how many cubic meters of water flow per minute?
在一根内直径为8cm的水管中．水流速度是每分250m，那么每分流过的水有多少立方米？
<gadget id="calculator">8 / 100</gadget>
<output>2/25 = around 0.08</output>

<gadget id="calculator">(2/25) / 2</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">(1/25) ** 2</gadget>
<output>1/625 = around 0.0016</output>

<gadget id="calculator">3.14 * (1/625) * 250</gadget>
<output>1.256</output>

<result>1.256</result>