Xiao Ming goes to school in the morning, walks 300 meters west and then 200 meters south, and he arrives at the school. This morning, Xiao Ming walked westward for 300 meters. He remembered that he had forgotten his math books, so he went home to get them, and then went to school. How many meters did he walk to school?
小明早晨上学，出门向西走300米，再向南走200米，就到学校了．今天早晨小明向西走到300米处，想起忘带数学书了，又回家拿，再去学校，这时他上学一共走了多少米？
<gadget id="calculator">300 * 2</gadget>
<output>600</output>

<gadget id="calculator">600 + 200</gadget>
<output>800</output>

<result>800</result>