The original price of a commodity in a supermarket is 100 yuan, the price is reduced (1/10) during the "May 1st" period, and the price is increased (1/10) after the "11th". How much is it?
超市某商品的原价是100元，"五一"期间降价(1/10)，"十一"之后又涨价(1/10)，这种商品在"五一"和"十一"期间各是多少元？
<gadget id="calculator">1 / 10</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">100 * (9/10)</gadget>
<output>90</output>

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

<gadget id="calculator">90 * (11/10)</gadget>
<output>99</output>

<result>99</result>