A snail climbs a tree 9m high, ascends lm during the day, and descends (1/3)m at night. How many days does it take to reach the top of the tree from a certain morning?
一只蜗牛，爬9m高的树，白天上升lm，夜间下滑(1/3)m．它从某日早晨开始向上爬，多少天后可以到达树梢？
<gadget id="calculator">9 - 1</gadget>
<output>8</output>

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

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">8 / (2/3)</gadget>
<output>12</output>

<gadget id="calculator">12 + 1</gadget>
<output>13</output>

<result>13</result>