To build a new teaching building, the actual investment is 1.8 million yuan, which is 10% less than the original plan. How much is the original plan to invest?
新建一座教学楼，实际投资180万元，比原计划节约了10%．原计划投资多少万元？
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">180 / (9/10)</gadget>
<output>200</output>

<result>200</result>