[重点]主攻163827头,主攻490527尾.
1,排除490头,054百,381十,381尾.
2,铁卒:34,39,84,89.
3,三字现:342,347,392,397,842,847,892,879.
4,二定:X34X,X39X,X84X,X89X,X3X2,X3X7,X8X2,X8X7,XX42,XX47.
5,三定:X342,X347,X392,X397,X842,X847,X892,X897,134X,139X.
6,直码:1342,1347,1842,1847,1392,1397,1892,1897,6842,6847.