A bought a stock with RMB 1,000, and then resold it to B with a profit of 10%. B sold it back to A, but B lost 10%. Finally, A sold it to B at a discount of 10% of the price B sold to A. , how much profit does A make in stock trading?
甲用1000人民币购买了一种股票，然后转卖给乙，获利10%，乙又反卖给甲，但乙损失了10%，最后甲按乙卖给甲价格的九折又卖给了乙，甲在股票交易中盈利多少元
<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_000 * (11/10)</gadget>
<output>1_100</output>

<gadget id="calculator">1_100 - 1_000</gadget>
<output>100</output>

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

<gadget id="calculator">1_100 * (9/10)</gadget>
<output>990</output>

<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">990 * (9/10)</gadget>
<output>891</output>

<gadget id="calculator">990 - 891</gadget>
<output>99</output>

<gadget id="calculator">100 - 99</gadget>
<output>1</output>

<result>1</result>