Grandma Li wanted to draw out the largest square in a 40-meter-long rectangular land to make a sheepfold, and fence the rest of the land to make chicken coops. How many meters of fence are needed.
李奶奶想在一个长为40米的长方形地里，先划出一个最大的正方形地做羊圈，剩下的地用篱笆围起来做鸡窝．共需篱笆多少米．
<gadget id="calculator">40 * 2</gadget>
<output>80</output>

<result>80</result>