1/1987*1988+1/1988*1989+1/1989*1990+.+1/1997*1998+1/1998*199
1/1987*1988+1/1988*1989+1/1989*1990+.+1/1997*1998+1/1998*199
1988+1989*1987/1988*1989-1=?
1/1986*1987+1/1987*1988+1/1988*1989+1/1989*1990+1/1990=?
简便计算:1986*1987分之1+1987*1988分之1+1988*1989分之1+1989*1990分之1+199
1/1987*1988+1/1988*1989+1/1989*1990+……+1/1996*1997+1/1997*19
1988+1989×1987÷1988×1989-1=1989-1+1989×1987÷1988×1989-1
怎样计算1/1987*1988+1/1988*1989+1/1989*1990+1/1990
1\1986*1987+1\1987*1988+1\1988*1989+1\1989*1990+1\1990这个计算怎么
1988乘1989-1分之1988+1989乘1987
1988*1989-1分之1988+1989*1987 简算
118/121×13166又1/20÷41(1998+1989×1987)/(1988×1989-1)41又1/3×3/
(1990乘1990+1988乘1988+…+2乘2)-(1989乘1989+1987乘1987+…+1)