986乘89减987乘88(用简便计算)

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986乘89减987乘88(用简便计算)

986乘89减987乘88(用简便计算)
986乘89减987乘88(用简便计算)

986乘89减987乘88(用简便计算)
986x89-987x88
=987x89-987x88-89
=987-89
=898

986*89-987*88
=(986+1-1)*89-987*88
=987*89-89-987*88
=987*(89-88)-89
=987-89
=898

986x89-987x88=
(987-1)x(88+1)-987x88=
987x88-88+987-1987x88=
987-89
898

(987-1)(88+1)-987*88=987*88-88+987-1-987*88=898