The school playground is a rectangle with a length of 400 meters and a width of 200 meters. Xiao Ming walks 2 times along the side of the playground. How many meters did he walk in total?
学校操场长是400米，宽是200米的长方形，小明沿着操场边走2圈，他一共走了多少米？
<gadget id="calculator">400 + 200</gadget>
<output>600</output>

<gadget id="calculator">600 * 2 * 2</gadget>
<output>2_400</output>

<result>2_400</result>