The tree planting team originally planned to plant 900 trees in 18 days, but it took 15 days to complete the task. How many more trees are actually planted per day than originally planned?
植树小队原计划18天共植树900棵，实际用了15天就完成了任务．实际每天比原计划每天多植树多少棵？
<gadget id="calculator">9_000 / 15</gadget>
<output>600</output>

<gadget id="calculator">9_000 / 18</gadget>
<output>500</output>

<gadget id="calculator">600 - 500</gadget>
<output>100</output>

<result>100</result>