If you want to plant trees on a trapezoidal land with an upper base of 1 km, a lower base of 3 km, and a height of 400 meters, if 2,500 trees are planted per hectare, how many trees can be planted in this land?
要在一块上底1千米，下底3千米，高400米的梯形土地上种树，如果按每公顷种树2500棵计算，这块地一共能种树多少棵？
<gadget id="calculator">1 + 3</gadget>
<output>4</output>

<gadget id="calculator">400 / 1_000</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/5) / 2</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">4 * (1/5) * 100 * 2_500</gadget>
<output>200_000</output>

<result>200_000</result>