Xiao Fang has to walk 1 kilometer from home to school. He goes to school every morning and goes home after school in the afternoon. How many kilometers did he walk to and from school in March?
小方从家到学校要步行1千米．他每天早晨上学，下午放学回家，整个三月份上学和回家一共步行了多少千米？
<gadget id="calculator">31 - 10</gadget>
<output>21</output>

<gadget id="calculator">1 * 2 * 21</gadget>
<output>42</output>

<result>42</result>