Ding Ding’s home is 420 meters away from the school. One day he walked 160 meters to school and found that he forgot his Chinese textbook at home, so he went home to pick it up and went to school.
丁丁家距学校420米，一天他上学时走了160米，发现语文课本忘在家里了，又回家取后去上学，丁丁这次上学比平时多走了多少米？
<gadget id="calculator">160 * 2</gadget>
<output>320</output>

<result>320</result>