Xiao Ming's home is 2.5 kilometers away from the school. He goes back and forth twice a day, how many kilometers does he have to walk in a week (in 5 days).
小明家离学校2.5千米，他每天往返两次，一周(按5天)要走多少千米．
<gadget id="calculator">2.5 * 4 * 5</gadget>
<output>50</output>

<result>50</result>