It is 250 meters from Xiaoming's house to the supermarket. How many kilometers did he travel back and forth twice a day?
小明家到超市250米，一天他往返两次共行了多少千米．
<gadget id="calculator">4 / 1_000</gadget>
<output>1/250 = around 0.004</output>

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

<result>1</result>