把循环小数化成分数（1）0.43 43的循环 （2）0.67 67的循环 （3）0.6345 45的循环改：（2）0.6

(1) X=0.43 43的循环 100X=43.43(循环) 100X-X=43 X=43/99
(2) X=0.67 7循环 100X=67.7(循环) 10X=6.7(循环) 100X-10X=61 X=61/90
(3) X=0.6345 45循环 10000X=6345.45(循环) 100X=63.45(循环) 10000X-100X=6345-63=6282 x=6282/9900=1047/1650