Grandma Wang’s house has a square chicken coop with a side length of 20 meters. One side of the chicken coop is against the wall. If you want to fence the other three sides, how many meters of fence do you need?
王奶奶家有一个正方形的鸡舍，边长20米，鸡舍一面靠墙，要在别外的三面围上篱笆，需要围多少米篱笆？
<gadget id="calculator">20 * 3</gadget>
<output>60</output>

<result>60</result>