Dr. Long gave Ou Ou a full bottle of drink, which contained 100 grams of fresh bamboo juice with a concentration of 80%. Oou drank 40 grams of fresh bamboo juice in the bottle, and then filled the bottle with water; after stirring, drank 40 grams of fresh bamboo juice in the bottle, and then filled it up with water. After repeating this three times, what is the concentration of the fresh bamboo juice in the bottle?
龙博士送给欧欧一满瓶饮料，里面装着100克浓度为80%的鲜竹汁．欧欧喝掉瓶中的40克鲜竹汁，然后用清水将瓶加满；搅拌后再喝掉瓶中的40克鲜竹汁，然后再用清水加满．如此反复三次后，瓶中鲜竹汁的浓度是多少？
<gadget id="calculator">100 - 40</gadget>
<output>60</output>

<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(4/5) / 100</gadget>
<output>1/125 = around 0.008</output>

<gadget id="calculator">60 * (1/125)</gadget>
<output>12/25 = around 0.48</output>

<gadget id="calculator">(12/25) / 100</gadget>
<output>3/625 = around 0.0048</output>

<gadget id="calculator">60 * (3/625)</gadget>
<output>36/125 = around 0.288</output>

<gadget id="calculator">(36/125) / 100</gadget>
<output>9/3_125 = around 0.00288</output>

<gadget id="calculator">60 * (9/3_125)</gadget>
<output>108/625 = around 0.1728</output>

<result>108/625 = around 0.1728</result>