Xiao Ming's home is 320 meters away from the school, and he has to go back and forth twice a day. How many meters does he have to walk in total?
小明家离学校320米，一天要往返两次，他一共要走多少米？
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">320 * 4</gadget>
<output>1_280</output>

<result>1_280</result>