Xiao Ming ran around a square vegetable field with a side length of 20 meters. How many meters did he run in total?
小明围着一个边长是20米的正方形菜地跑了一圈，他一共跑了多少米？
<gadget id="calculator">20 * 4</gadget>
<output>80</output>

<result>80</result>