A snail climbs up from the bottom of the well, climbs up to (1/2) the depth of the well during the day, and retreats to climb part (1/2) when resting at night. According to this calculation, how many days does it take for the snail to climb to the edge of the well.
一只蜗牛从井底向上爬，白天爬上井深的(1/2)，晚上休息时又退下爬上部分的(1/2)．照这样计算，蜗牛多少天才能爬到井沿上去．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) * (1/2)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / (1/4)</gadget>
<output>4</output>

<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<result>3</result>