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＝ 1/30+1/42+1/56+1/72+1/90 1／2 + 1／6 + 1／12 + 1／20 + 1／30+ 1／42 + 1／56 + 1／72＝ 1/30+1/42+1/56+1/72 1/30+1/42+1/56+1/72简便算法 1/30+1/42+1/56+1/72 简算 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72 30／1＋42／1＋56／1＝? 1/2+1/6+1/20+1/30+1/42+1/56+1/72等于几? 1/12+1/20+1/30+1/42+1/56+1/72+1/90=? 1/2+1/6+1/20+1/30+1/42+1/56+1/72等于多少?