1-1+30-56

1-1+30-56 1/30+1/42+1/56+1/72+1/90 1/30+1/42+1/56+1/72+1/90 1/30+1/42+1/56+1/72 简算 1/30+1/42+1/56+1/72简便算法 1/20+1/30+1/42+1/56简便计算, 1/30+1/42+1/56+1/72＝ 简算1/30+1/42+1/56+1/72＝? 1/30+1/42+1/56+1/72= 1/20+1/30+1/42+1/56=1/20+1/30+1/42+1/56= 30／1＋42／1＋56／1＝? 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72 1+1/2+1/12+1/6+1/20+1/30+1/40+1/56 30分之1+42分之一+56分之1+72分之一 1/2+1/6+1/12+1/20+1/30+1/42+1/56 简算 1/2+1/6+1/12+1/20+1/30+1/42+1/56简算, 1/12+1/20+1/30+1/42+1/56+1/72+1/90