0.122.循环 + 2/5
= 0.1 + 0.022.循环 + 2/5
= 1/10 + 2×0.011111循环 + 2/5
= 1/10 + 2/90 + 2/5
= （9+2+18）/90
= 29/90
再问： 是二的循环
再答： 知道，前边不就是0.12222222......吗？
再问： 哦
再答： 最后统分错了一步，应为：
0.122....循环 + 2/5
= 0.1 + 0.022....循环 + 2/5
= 1/10 + 2×0.011111循环 + 2/5
= 1/10 + 2/90 + 2/5
= （9+2+36）/90
= 47/90
如果是：
0.12+0.22222循环+2/5
= 3/25+2×0.11111循环+2/5
= 3/25+2×1/9+2/5
= 3/25+2/9+2/5
= 27/225+50/225+90/225
= 167/225
