超難的問題,有冇人解答到?

食到第 19 粒糖嘅時候,你只有一張糖紙,

問別人借一粒糖,食咗佢就有 20 粒;

再用餘下的兩張紙換回一粒糖還番畀人.

當同學一邊食糖,一邊將糖紙換到了糖,Total 20 !1

Very Easy !!

買了10粒糖,借了10張糖紙
淨20張糖紙(吃了10粒)
換成了10粒糖(吃了第10~20粒)
得返10張糖紙
還返借的10張糖紙
這是IQ題

2008-03-24 17:41:25 補充：
這間糖果店好蠢
變了買一送一

2008-03-24 17:53:03 補充：
寫多次:
買了10粒糖,另外問人借了10張糖紙
吃了第1-10粒
淨10張糖紙+借的十張糖紙=20張,
再換成了10粒糖,吃了第11~20粒)
又得返10張糖紙
再還返佢借的10張糖紙

2008-03-26 18:54:14 補充：
如果以吃完再換,再吃,再換,
結果你最多只換到18粒
(1-10粒;換;11-15粒;換;16-17粒+1紙;換;第18粒+1糖紙)
如果比你最尾可以借一張糖紙(大概係你諗到既方法)
最多有埋第19粒,之後還返糖紙比人,咁你就一無所有
所以應該得我上面個方法先有廿粒

if he goes and exchange the candy from the first two candies...
m then use the new candy + another candy he bought to exchange another free candy, you will get 20.

Let A be the original candy he bought
B = free candy

A + A = B

Then use another A + B to get another B

then A +B again to get another B....

He should have 10A....you can calculate how many he will get from B.
2A = B
10A can change for 5B
since B = 2A

therefore 10A can change for 10A total = 20A loh..

Not sure if you get me though...