The inner diameter of the water pipe is 20 cm, and the velocity of water in the pipe is 8 cm per second. A classmate went to wash his hands and forgot to turn off the tap when he left. How many liters of water was wasted in 5 minutes.
自来水管的内经是20cm，水管内水的流速是每秒8cm．一位同学去洗手，走时忘记关掉水龙头，5分钟浪费水多少升．
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">60 / 1_000</gadget>
<output>3/50 = around 0.06</output>

<gadget id="calculator">3.14 * 100 * 8 * 5 * (3/50)</gadget>
<output>753.6</output>

<result>753.6</result>