There is a row of trees beside the road. There are 401 trees from the first tree at point A to the last tree at point B. It is known that the distance between every two adjacent trees is 2.5 meters. How many kilometers is the distance between A and B?
公路旁有一排树，从A点第一棵树起到B点最后一棵树共有401棵，已知每相邻两棵树之间的距离是2.5米，AB间距多少千米？
<gadget id="calculator">401 - 1</gadget>
<output>400</output>

<gadget id="calculator">2.5 / 1_000</gadget>
<output>0.0025</output>

<gadget id="calculator">400 * 0.0025</gadget>
<output>1</output>

<result>1</result>