Question

将循环小数0.21化为分数的方法如下：设0.21=X,则100x=21+0.21=21+x∴99x=21∴x=21/99

Answer 1

0.9=x;

乘以10,9+x=9.9=10x;

x=1;

0.31=x;

乘以100,31+x=31.313131=100x;

x=31/99