Plant trees around a square pond (every corner must be planted), plant 121 trees on each side, and the distance between every two trees is 4 meters. What is the perimeter of the pond in meters?
在正方形池塘的四周种树(每个角上都要种)，每边种树121棵，每两棵树之间的距离是4米，这个池塘的周长是多少米？
<gadget id="calculator">121 - 1</gadget>
<output>120</output>

<gadget id="calculator">4 * 120</gadget>
<output>480</output>

<gadget id="calculator">480 * 4</gadget>
<output>1_920</output>

<result>1_920</result>