Xiaoqing's distance from home to school is 500 meters, and he has to walk back and forth three times a day. How many kilometers does he have to walk in a week?
小青从家到学校的距离是500米，他每天都要走3个来回，他一个星期要走多少千米的路程？
<gadget id="calculator">7 / 1_000</gadget>
<output>7/1_000 = around 0.007</output>

<gadget id="calculator">500 * 2 * 3 * (7/1_000)</gadget>
<output>21</output>

<result>21</result>