Plant trees on both sides of a path with a total length of 2 kilometers. How many trees should be planted every 50 meters (both ends are planted).
在一条全长2千米的小路两旁种树，每隔50米种一棵(两端都种)共要种多少棵．
<gadget id="calculator">1_000 / 50</gadget>
<output>20</output>

<gadget id="calculator">2 * 20</gadget>
<output>40</output>

<gadget id="calculator">40 + 1</gadget>
<output>41</output>

<gadget id="calculator">41 * 2</gadget>
<output>82</output>

<result>82</result>