解法一
0.99999…=0.33333… *3=1/3 *3=1

解法二
令0.99999…=x
=> 9.99999…=10x
=> 9.99999…-0.99999…=10x-x=9x
所以9x=9 => x=1
即0.99999…=1

解法三
1/9=0.11111…
2/9=0.22222…
……
8/9=0.88888…
所以9/9=0.99999…=1

科学是神奇的东西，但怎么就觉得我们是在自找麻烦呢？

Technorati : 数学

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