The distance between Xiao Ming's home and school is 450 meters. He goes home for lunch every day and has to go back and forth twice a day. How many meters does he have to walk in total?
小明家到学校相距450米，他每天中午回家吃饭，一天需往返两次，一共要走多少米．
<gadget id="calculator">450 * 4</gadget>
<output>1_800</output>

<result>1_800</result>