There are 10 liters of pure alcohol in a container. After pouring out 1 liter, fill it up with water, pour out another 1 liter, fill it up again with water, then pour out 1 liter again, and fill it up with water. At this time, the concentration of the alcohol solution in the container is How many?
一容器内装有10升纯酒精，倒出1升后，用水加满，再倒出1升，再用水加满，然后再倒出1升，用水加满，这时容器内的酒精溶液浓度是多少？
<gadget id="calculator">10 - 1</gadget>
<output>9</output>

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

<gadget id="calculator">9 - (9/10)</gadget>
<output>81/10 = around 8.1</output>

<gadget id="calculator">(81/10) / 10</gadget>
<output>81/100 = around 0.81</output>

<gadget id="calculator">(81/10) - (81/100)</gadget>
<output>729/100 = around 7.29</output>

<gadget id="calculator">(729/100) / 10</gadget>
<output>729/1_000 = around 0.729</output>

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

<gadget id="calculator">(729/1_000) * 1</gadget>
<output>729/1_000 = around 0.729</output>

<result>729/1_000 = around 0.729</result>