A swimming lane is 50 meters long, and Xiao Ming swam 2 back and forth, how many meters did he swim in total?
一条游泳道长50米，小明游了2个来回，共游了多少米．
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">50 * 4</gadget>
<output>200</output>

<result>200</result>