There is a square playing field with a side length of 200 meters. Plant a tree every 10 meters along the perimeter of the playground. How many plants do you need in total?
有一个正方形的运动场，边长是200米．沿运动场的周围每隔10米栽一棵树．一共需要栽多少颗？
<gadget id="calculator">4 / 10</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">200 * (2/5)</gadget>
<output>80</output>

<result>80</result>