最佳答案：答案：(1) 设0.aaa......＝s a.aaa.....＝10sa＝9ss＝a/9 0.aaa...＝a/9例如:0.555....＝5/9(2）设0.abab...
答案：
(1) 设0.aaa......＝s
a.aaa.....＝10s
a＝9s
s＝a/9 0.aaa...＝a/9
例如:0.555....＝5/9
(2）设0.abab......＝s
ab.ab....... ＝100s
ab ＝99s
s＝ab/99 0.abab...＝ab/99
例如:0.3838....＝38/99
(3）设0.abcabc......＝s
abc.abc.......＝1000s
abc＝999s
s＝abc/999
0.abcabc...＝abc/999
例如:0.357357....＝357/999
(4）设0.abcdcd......＝s
ab/100+0.00cdcd....... ＝s
ab/100+cd/9900 ＝s
(99*ab+cd)/9900 ＝s
(ab00-ab+cd)/9900＝s
即0.abcdcd......＝(ab00-ab+cd)/9900 例如:0.123434...＝(1200+34-12）/9900
＝1222/9900
