If the price of an item was increased by 10% last year, and the price is reduced by 10% this year, what percentage is the current price of last year before the price increase?
一件物品去年提价10%，今年比去年降价10%，现在的售价是去年提价前售价的百分之几？
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 + (1/10)</gadget>
<output>11/10 = around 1.1</output>

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

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

<gadget id="calculator">1 * (11/10) * (9/10)</gadget>
<output>99/100 = around 0.99</output>

<result>99/100 = around 0.99</result>