A person uses a rope to measure the depth of a well. Fold the rope in half and measure it. There is 6 meters outside the well. Fold the rope three times and measure it. It is exactly equal to the depth of the well. How deep is the well in meters?
一个人用绳子测量一口井的深度，把绳子对折后量，井外余6米，把绳子3折后量，正好等于井深，这口井深多少米．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/2) - (1/3)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">6 / (1/6)</gadget>
<output>36</output>

<gadget id="calculator">36 * (1/3)</gadget>
<output>12</output>

<result>12</result>