Xiao Ming runs around a square nursery with a side length of 42 meters. He runs 5 laps, how many meters in total?
小明围着一个边长42米的正方形苗圃跑步，他跑5圈，共跑多少米？
<gadget id="calculator">42 * 4 * 5</gadget>
<output>840</output>

<result>840</result>