To build a residential building, the original planned investment was 500,000 yuan, but the actual investment was 400,000 yuan. How much was the actual savings compared to the original plan?
修建一座居民楼，原计划投资50万元，实际投资40万元，实际比原计划节约了百分之几？
<gadget id="calculator">50 - 40</gadget>
<output>10</output>

<gadget id="calculator">10 / 50</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>