There is a pile of coal in the factory that was originally planned to burn 0.2 tons per day, which can be burned for 36 days. After technical improvement, only 0.18 tons of coal can be burned per day. How many days longer can this pile of coal be burned than originally planned?
工厂有一堆煤原计划每天烧0.2吨，可以烧36天．技术改良后每天只烧0.18吨，这堆煤可以比原计划多烧多少天？
<gadget id="calculator">0.2 / 0.18</gadget>
<output>1.111111</output>

<gadget id="calculator">36 * 1.111111</gadget>
<output>39.999996</output>

<gadget id="calculator">39.999996 - 36</gadget>
<output>3.999996</output>

<result>3.999996</result>