How to make 7 from four 2

2008-07-26 5:34 pm
Four "2" digits to make the result 7 using any mathematical means. Says,

2 -2 + 2 - 2 = 0
2 - 2 + 2/2 = 1

and etc.

回答 (3)

2008-07-27 7:14 pm
我想到兩個方法:

方法一:
如果我將問題看成這四個"2"是用火柴砌成的羅馬數字,即:

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那麼,我可以用下面的方法將火柴重新排列便可得到"7":

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方法二:
2 ( 2 x 2 - 2^(-1) )
2008-07-26 6:13 pm
你俾5個2我就得
2008-07-26 6:13 pm
It is not possible


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