Xiaoxin's home is 900 meters away from the school. One morning, when he went to school from home, when he walked 300 meters, he found that he had forgotten to bring his math books. So he went home to get the book and went to school again. How many meters did Xiaoxin walk this morning?
小新家离学校900米．一天早晨，他从家到学校上学，走到300米时，发现忘记带数学书．于是他又回家拿书，再去学校．小新这天早晨多走多少米？
<gadget id="calculator">300 * 2</gadget>
<output>600</output>

<gadget id="calculator">600 + 900</gadget>
<output>1_500</output>

<result>1_500</result>