The price of a certain brand of computer is reduced by 10% during the National Day promotion, and the price will be increased by 10% after the promotion is over. Has the price of this brand of computer before the event increased or decreased compared to the price after the event? What is the magnitude of the change?
某品牌电脑在国庆促销中降价10%，促销活动结束后再涨价10%．这一品牌电脑活动前价格和活动后价格相比是涨了还是降了？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">(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>