上期:百位:7 十位:4 个位:9 和值:4+7+9=20
3d021期推荐参：
一,本期杀码：9
二,本期胆码：048
三,六码推荐: 024578
四,五码推荐：02478
五,四码推荐：0478
六,17注: 024,025,034,035,048,057,068,237,246,257,347,358,367,368,378,458,468
七,单选34注：034,035,042,048,068,075,204,205,237,264,275,304,305,347,367,368,372,374,378,502,507,538,548,572,608,637,638,642,648,804,835,837,845,864
八,跨度推荐: 4,5,7,8
九,和值推荐：12,14,16,17,18