Now it is necessary to plant trees on a green land of 2 square kilometers. If one tree is planted every 5 square meters, how many thousands of trees are needed in total.
现要在一块2平方千米的绿地上植树，若每5平方米植一棵树，一共需要多少万棵树．
<gadget id="calculator">1_000_000 / 5 / 10_000</gadget>
<output>20</output>

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

<result>40</result>