The number of dust storms this spring is 90% of that of last year. How much is this year less than last year?
今年春天沙尘暴的次数是去年的90%，今年比去年减少多少．
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">1 - (9/10)</gadget>
<output>1/10 = around 0.1</output>

<result>1/10 = around 0.1</result>