2/3+2/15+2/35+2/63
2/3+2/15+2/35+2/63+2/99
1/3+2/8+2/15+2/24+2/35+2/48+2/63+2/80
2/15+2/35+2/63+2/99+2/143
简便计算:3/2+15/2+35/2+63/2+99/2+143/2
2/3+2/15+2/35+2/63+2/99+2/132
简算题 3/2+15/2+35/2+63/2+99/2+143/2=?
2/3+2/15+2/35+2/63+2/99+2/143=?
3/2+15/2+35/2+63/2+99/2+132/2的简便算法
找规律:1/3,-2/15,3/35,-4/63
找规律1/3 -2/15 3/35 -4/63
找规律:1/3,-2/15,3/35,-4/63( ),( )
简便计算:20-2/3-2/15-2/35-2/63-2/99