Xiao Ming's home is 100 meters away from school. If Xiao Ming walks back and forth to school 3 times, how many meters does he walk?
小明家到学校有100米，如果小明到学校来回走3趟，那么他走了多少米．
<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">100 * 6</gadget>
<output>600</output>

<result>600</result>