MATHS

一日4公尺,5日就20公尺
20/(6-2)=5

So,5天之後這隻蝸牛才能爬出這口井

First day: The snail climbs 6 meter,it need to climb 14 meters more. At night, it slide 2 meter and it had climb 4 meters

Second day:The snail climbs to 10 meters and slide 2 meters,it had climbed 8 meters

Third day:It climbs to 14 meters and slide 2 meters, it had climbed 12 meters

Fourth day,It climb to 18 meters and slide 2 meters,it had climbed 16 meters

Firth day,It climbs out the well

一天裏白天向上爬6公尺，晚上向下滑2公尺，所以第一天上升6–2=4(公尺)，即第二天早上從離井底4公尺的地方開始爬，第三天早上從離井底8公尺的地方開始爬，……依此推算，到第五天早上從離井底 16公尺的地方開始爬，不用到晚上就已經出來了。

5天
easy!!!

2007-11-05 18:47:17 補充：
4.6666666666666666666.......................................................是CORRECT

Day 1: -20+6-2=-16
Day 2: -16+6-2=-12
Day 3: -12+6-2=-8
Day 4: -8+6-2=-4
Day 5: -4+6>0 and it will not drop at night as it reaches the ground already

so answer = 5 days

即係每日會上4公尺(6-2)
咁4成5等於20
所以要5日就得啦!

一天裏白天向上爬6公尺，晚上向下滑2公尺，所以第一天上升6–2=4(公尺)，即第二天早上從離井底4公尺的地方開始爬，第三天早上從離井底8公尺的地方開始爬，……依此推算，到第五天早上從離井底 16公尺的地方開始爬，不用到晚上就已經出來了。