Shihu District has a green area of 1.5 hectares. If one tree is planted every 3 square meters, how many trees are needed?
石湖小区有绿化面积1.5公顷，如果每3平方米种一棵树，那么需要多少棵树．
<gadget id="calculator">1.5 * 10_000</gadget>
<output>15_000</output>

<gadget id="calculator">15_000 / 3</gadget>
<output>5_000</output>

<result>5_000</result>