A product is sold at a 10% price reduction and then a 10% price increase. Has it decreased or increased compared to the original price? What is the magnitude of the change?
一件商品，先降价10%，再提价10%出售．与原价相比降了还是涨了？变化幅度是多少？
<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">1 + (1/10)</gadget>
<output>11/10 = around 1.1</output>

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

<gadget id="calculator">1 - (99/100)</gadget>
<output>1/100 = around 0.01</output>

<result>1/100 = around 0.01</result>